NATIONAL CENTER Series 22 

For HEALTH STATISTICS Number 8 

VITAL and HEALTH STATISTICS 

DATA FROM THE NATIONAL VITAL STATISTICS SYSTEM 

Variationsin 

Birth Weight 

legitimatelive Births 

United States -1963 

Statistics on the variation in birth weight accordi~g to w!”d-ter 

or not the mother was employed during pregnancy, 1962 family income, the time of the first visit for medical care and the 

number of visits during 

Based on data collected 

and medical care services 

of births in 1963 which 

for Health Statistics. 

U.S. DEPARTMENT OF HEALTH, 

Public Health 

Health Services and Mental 

the 12 months preceding childbirth. 

bya questionnaire mailed to mothers 

for a sample selected from records 

were filed with the National Center 

EDUCATION, AND WELFARE 

Service 

Health Administration 
Pyblic Health Service Publication No. 1000-Series 22-No. 8 

l— 

For sale &rnthe Superintendent of Documents, U.S. Government Printing Office 

OffIce, Washington, D. C., 20402- Price 45 cents 
NATIONAL CENTER FOR HEALTH STATISTICS 

THEODORE D. W(X)LSEY, DiTeCtOT 

PHILIP S.LAWRENCE, SC.D., Associate Director 

OSWALD K. SAGEN, PH.D.>,Assistant Director for Health Statistics Development 

WALT R. SIMMONS,M.A.,Assistant Director /or Research and Scientific Development 

ALICE M. WATERHOUSE, M.D.,Medical Consultant 

JAMES E. KELLY, D.D.S.,Dental Advisor 

EDWARD E. MINTY, Executive Officer 

MARGERY R. CUNNINGHAM, in/orrrzation O/ficer 

DIVISION OF VITAL STATISTICS 

ROBERT D.GROVE,Ph.D.,Director 

ROBERT A.ISRAEL,M.S.,Deputy Director


ROBERT A.ISRAEL,M.S.,Acting Chief, Mortality Statistics Branch


ROBERT D.GROVE, Ph.D.,Acting Chiej, Nata[ity Statistics Branch


LOREN E.CHANCELLOR, Chic/, Registration Methods Brarzck 

ALICEHETZEL, Chic/,Marriage and Divorce Statistics 13ranck 

ARNE B.NELSON,M.A.,Chic/,Vital Records Survey Branch 

MICHAEL J.ZUGZDA, Acting Cbie/, Statistical Resources Section 

Public Health Service Publication No. 1000-Series 22-No. 8 

Library of Congress Catalog Card Number 68-62240 
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CONTENTS 

Inmoduction


Selected Fin&ngs


Classification


Comparison of Survey and Registration Data ---------------------------


Employment During Pregnancy


Family Income


Visits for Medical Care DuringYear Before Childbirth


References


Detailed Tables


Appendix I. Technical Notes on Metiods


Background of ~is Report


Sources of Data -----------------------------------------------------


Sample Desi~----------------------------------------------------­


‘The Birth Certificate and Questionnaires


Collection of Data --------------------------------------------------


Processing ofData


Nonresponse and Imputation of Missing Data ---------------------------


Btiti Records


Physicians and Medical FaciEties


Esttiation


Reliability of Estimates


Roun&ng ofNukrs


Appendix H. Definitions of Certain Terms Used in This Report


Information From the Certificate of Live Birth


Information From the Questiomtire


Appendix III. Source Forms


Certificateof Live Birti


Mother Questiomafie


Physician Questio~aire


Hospital Questiom~re


1 

2 

2 

3 

4 

5 

7 

11 

12 

25 

25 

25 

25 

26 

26 

27 

27 

28 

28 

28 

29 

30 

31 

31 

31 

32 

32 

33 

34 

35 

... Ill 
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IN THIS REPORT statistics a?%presented on the variation in bivth 

weight among legitimate births in the United States in 1963. Estimates 

of the avevage bivth weight and the pevcent distribution of births by 

bi~th-weight intervals are @“venwhen the rnothen are classified by 

whether or not they weve employed during pvegnancy, by the family income in 1962, and by the timing and amount of medical cave dwing the 

12 months pveceding childbirth. 

These statistics ave based on data collected in a mail survey with questionnaires sent to the mo thev, the attending physician, the hospital where 

the bivth took place, and to any other physician, hospital, or othev medical facility named by one of the first three souvces. In cases where there 

was no response to thvee mailed questionnaires, followups by telephone 

or pevsonal interview weve attempted. 

The avevage bivth weight of all legitimate live bivths in 1963 was 3,280 

grams. Approximately 7.2 pevcent of the babies weighed 2,500 grams ov 

less and 8.0 pe~cent weighed 4,001 grams ov move. Babies born to 

mawied women who were employed duving pvegnancy had a lowev avevag-e birth weight than babies born. to women who weve not employed. 

However, employed women had fewev babies of low bivth weight (2,500 

g-rams ov less) than women who weve not employed. Mawied women in 

families with low incomes in i962 had a highev pwcentage of babies 

weighing 2,500 grams ov less than women in families with high incomes. Mavvied women who made 10 visits ov move to physicians ov 

mti.iical facilities during the year had fewev low-birth-weight babies 

than women who made fewev than 10 visits. 

SYMBOLS 

Data not available 

Category not applicable . . . 

Quantity zero -

Quantity more than O but less than 0.05---- 0.0 

Figure does not meet standards of 

* reliability or precision 

iv 
VARIATIONS IN BIRTH WEIGHT


1963 LEGITIMATE LIVE BIRTHS 

Mary Grace Kovar, Division of Vital Statistics 

INTRODUCTION 

It has long been recognized that birth weight 

is a factor in the survival of the newborn. Earlier 

studies published in the Vital and Health Statistics 

series (Series 21, Nos. 3-6) have examined the 

relationship between birth weight and survival. 

These studies, which were based on matched birth 

and death records for infants who were born during 

the first quarter of 1950 and who died within 28 

days after birth, amply demonstrate the increased 

risk of early death for the low-birth-weight baby. 

There were, for example, 173.7 deaths per 1,000 

live births weighing 2,500 grams or less as contrasted with 7.8 deaths per 1,000 live births 

weighing 2,501 grams or more. 

The present report contains no information 

about death rates. It is instead an attempt to 

examine some of the factors operating on the 

family or the mother before the birth which might 

affect the weight of the child. The three items 

which were selected for study are employment of 

the mother during pregnancy, family income, and 

timing and number of visits for medical care 

during the year before childbirth. 

These data became available from the 1963 

National Natality Survey which was designed to 

obtain estimates of the amount of exTosure to 

radiation during pregnancy. The number of visits 

to a physician or medical facility, the mother’s 

employment during pregnancy, and the income of 

the family in the previous calendar year (1962) 

were obtained in the course of the study of X-ray 

exTosure. Color, the birth weight of the child, the 

age of the mother, and the number of previous live 

births were availabIe from the birth certificate. 

By combining the information received from the 

mother with that recorded on the certificate, it 

became possible to examine additional conditions 

which might affect the birth weight. 

Through a process of ratio adjustment, the 

data obtained from the survey were converted into 

national estimates so that persons familiar with 

the statistics from the vital registration system 

can use these data in conjunction with the vital 

statistics. However, because these data are from 

a sample survey, the estimates will not always 

agree with those which would be obtained from the 

complete file of registered births. In addition, the 

data contained in this report are subject to sampling error and the reader should consult the 

tables of sampIing error in appendix I before 

deciding that there are real differences in birth 

weights among the various groups of women. 

The necessity of allowing for sampling variability in making comparisons between birth 

weights is one reason for showing the average or 

arithmetic mean rather than the median weight as 

is usual in vital statistics reports. Although it is 

possible to compute the sampling errors of the 

median, it is much easier to do so for a mean— 

particularly in this case where the computer 
program was already available. Those readers 

who prefer the median can make an approximation 

from the frequency distribution. However, as 

shown later in the report, in the relatively symmetrical distribution of live-birth weights, there 

is little difference between the average and the 

median. 

Appendix I describes the design and procedures of the survey and the methods of obtaining 

the estimates. 

Appendix II gives definitions of terms used 

in this report and appendix III consists of facsimiles of the Standard Certificate of Live Birth 

and of the questionnaires which were mailed to the 

mothers, physicians, and medical facilities. 

SELECTED FINDINGS 

During 1963 an estimated 3.8 million legitimate babies were born in the United States. Their 

average birth weight was 3,280 grams. Approximately 7.2 percent of the babies weighed 2,500 

grams or less and 8.0 percent weighed 4,001 

grams or more. The average birth weight of babies 

born to married white women was 3,300 grams 

and 6.5 percent of the babies weighed 2,500 grams 

or less. The average birth weight of babies born 

to married nonwhite women was 3,130 grams and 

11.8 percent weighed 2,500 grams ?r less. 

On the average, babies born to married 

women who were not employed during pregnancy 

weighed 3,290 grams and babies born to married 

women who were employed during pregnancy 

weighed 3,250 grams. However, approximately 

7.6 percent of the babies born to women who were 

not employed weighed 2,500 grams or less but 

only 6.5 percent of the babies born to women who 

were employed during pregnancy weighed 2,500 

grams or less. Among women who were employed, 

those who stopped working during the second 

trimester of pregnancy appeared to have babies 

with a lower average weight and to have more 

babies of low birth weight than women who stopped 

working in the first trimester or women who 

continued working into the third trimester of 

pregnancy. 

Babies born to married women in the lower 

income classes weighed less on the average than 

babies born to women in the higher income 

classes. The percentage of babies weighing 2,500 

grams or less was almost twice as high in families 

with an income of under $3,000 in 1962 as in 

families with an income of $7,000 or over. Within 

each income class, babies born to nonwhite mothers had a lower average birth weight and were 

more likely to weigh 2,500 grams or less than 

babies born to white mothers. For example, in 

families with a 1962 income of under $3,000, 8.8 

percent of the babies born to white mothers and 

14.0 percent of the babies born to nonwhite 

mothers weighed 2,500 grams or less. In families 

with a 1962 income of $7,000 or more, 5.4 percent 

of the babies born to white mothers and 9.6 percent of the babies bom to nonwhite mothers 

weighed 2,500 grams or less. 

Babies born to married white women who 

received medical care before the end of the first 

trimester of pregnancy were less likely to weigh 

2,500 grams or less than babies born to women 

who either did not receive care until later in pregnancy or who received no prenatal care. Babies 

born to nonwhite married women who received 

medical care before the end of the first trimester 

of pregnancy were more likely to weigh 2,500 

grams or less than babies born to women who 

did not receive care until later in pregnancy or 

who received no prenatal care. Although no data 

are available from this survey to explain the difference, some suggestions as to possible explanations based on data from other sources are 

made in the text. 

Over 10 percent of the married women who 

had fewer than 10 visits to physicians or medical 

facilities during the 12 months before childbirth 

had babies which weighed 2,500 grams or less. 

Approximately 5 percent of the women who made 

10 visits or more had babies which weighed 2,500 

grams or less. 

Classification 

In almost all areas birth weight was reported 

in pounds and ounces. Gram groupings have been 

used here in order to facilitate comparison with 

other studies and to make the arithmetic computations and comparisons more efficient. The 

2 
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equivalents of these groups in terms of pounds 

and ounces are as follows: 

1,000 grams or less = 2 lb. 3 oz. or less 

1,001-1,500 grams = 2 lb. 4 oz.-3 lb. 4 oz. 

1,501-2,000 grams = 3 lb. 5 oz.-4 lb. 6 oz. 

2,001-2,500 grams = 4 lb. 7 oz.-5 lb. 8 oz. 

2,501-3,000 grams = 5 lb. 9 oz.-6 lb. 9 oz. 

3,001-3,500 grams = 6 lb. 10 oz.-7 lb. 11 oz. 

3,501-4,000 grams = 7 lb. 12 oz.-8 lb. 13 oz. 

4,001-4,500 grams = 8 lb. 14 oz.-9 lb. 14 OZ. 

4,501-5,000 grams = 9 lb. 15 OZ.-11 lb. O oz. 

5,001 grams or more=ll lb. 1 oz. or more 

For purposes of discussion, infants weighing 

2,500 grams or less have been referred to as 

low- birth-weight babies. This term is used on the 

recommendation of the World Health Organization 

and medical groups in the United States and refers 

only to the weight of the child at birth with no 

implications as to length of gestation or any other 

measure of maturity. 

Comparison of Survey and 

Registration Data 

Color, age of mother, and live-birth order 

are all recorded on the birth certificate. Therefore, the statistics presented in tables 1 and 2 

for legitimate births from the survey can be compared with vital statistics data for all United 

States births in 1963. 

Table A shows the percent distribution of 

births by birth-weight intervals for all births 

from the vital registration system and for legitimate oirths from the i\iatioi~al ihk~tality Survey. 

The two distributions are very similar. In addition, the median for all registered births was 

3,290 grams and the average for the legitimate 

births in the survey was 3,280 grams. 

Another comparison of the two sets of data 

is shown in table B. In this table the median 

weights (the only measure available from published data) from the registration system are 

shown with the average weights of the babies 

selected in the survey for age of mother and color 

classes. There is a tendency for the average to 

be lower than the median for births to women 

under age 25 and aged 35 or older, but higher for 

births to women aged 25-34. The average is also 

Iower than the median for each color class. The 

differences are slight except for births to women 

aged 35 or over. For some reason, the average 

birth weight is low for women 35 years or over 

in the survey—lower than would be expected from 

previous experience with registration statistics. 

IrJ an effort to discover the reason for this, the 

average birth weight was computed for all sample 

births to women in this age group instead of just 

for legitimate births. The average birth weight of 

all of the births to women aged 35 or over selected 

in the sample was 3,280 grams. Thus, the difference between survey and registration data was 

not due to restricting the survey to legitimate 

births. 

Table 2 is the last of the introductory tables 

based on information recorded on the birth cerTable A. Percent distribution of births. 

by birth-weight intervals according t; 

estimates from vital registration data 

and Nati-onal Natakity 

States, 1963 

Birth weight 

Total 

1,000 grams or less 

1,001-1,500 grams 

1,501-2,000 grams 

2,001-2,500 grams 

2,501-3,000 grams 

3,001-3,500 grams 

3,501-4,000 grams 

4,001-4,500 grams 

4,501-5,000 grams 

5,001 grams or more---

Survey: United 

Percent 

distribution 

100.0 100.0 

0.6 

0.7 ::; 

1.5 

5.4 ;:: 

19.4 19.4 

38.2 39.2


25.8 26.1


::: :::


0.2 0.1


lNational Center for Health Statistics: 

Vital Statistics of the United States, 

1963, Vol. I, Natality. Public Health 

Service. Washington. U.S. Government 

Printing Office, 1965. 

3 
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tif icate. The average weight and the percent 

distribution by birth weight intervals are shown 

for each of the first three and for the fourth and 

higher birth orders for each color. The average 

birth weight was higher for each succeeding birth 

order. Within each birth order the average weight 

of white births was higher than the average weight 

of nonwhite births. For first and second births the 

difference was almost 300 grams. For third births 

it was 170 grams; for fourth and high order births 

it was 100 grams. However, as has been shown 

in earlier reports in this series, the proportional 

distribution of nonwhite births within the category 

“fourth or higher” is not the same as that of 

white births. Therefore, the effects of order and 

color are confounded in the final category. 

Two things are apparent from this exposition 

of tables 1 and 2 and their comparison with regTable B. Median and average birth weights, 

by age of mother and color; estimates 

from vital registration data and National Natality Survey: United States, 

1963 

Weight at birth 

in grams 

Age of mother 

and color 

All Legitbirthsl ima te 

births 

Medi,an Average 

All ages 3,290 3,280 

Under 15 years 

15-19 years 

3,040 

3,220 } 3,180 

20-24 years 3,280 3,250 

25-29 years 3,310 3,320 

30-34 years 3,330 3,340 

35-39 years 

40-44 years 

3,340 

3,360 3,290 

45 years and over 3,380 1 

white 3,320 3 ;300 

Nonwhite 3,140 3,130 

lNational Center for Health Statistics: 

Vital Statistics of the United States, 

1963, Vol. I, Natali_ty. Public Health 

%ice. Washington. U.S. Government 

Printing 0ffice,-1965. 

istration data. First, the average birth weight is 

not strikingly different fromthe median commonly 

used in publications based on.the registration 

system. The reader accustomed to the one can 

use the other. Second, the percent distributions 

by birth-weight intervals are very close; this 

gives confidence that the survey, which is based 

on a sample, accurately represents births from 

the full file of registered births. 

Employment During Pregnancy 

In a previous report in this seriesl it was 

noted that a relationship between employment 

during pregnancy and birth weight, thus possibly 

between employment of the mother and survival 

of the child, has been suspected. Tables 3and4 

present the birth weight distributions for each 

age and color category for certain classes of 

employment during pregnancy. 

When the average birth weight of babiesof 

employed wives is compared with that of babies 

of wives who were not employed, it is obvious 

that, within each age-of-mother interval, the 

average birth weight of children of employed 

wives was less than that of children of wives 

who were not employed. The differences in each 

interval are not significant but they are consistent. The lower average weight does not mean, 

however, a greater incidence of babies weighing 

2,500 grams or less born to the employed wives. 

0nly6.5 percent of the babiesof employedwomen 

weighed 2,500 grams or less while 7.6 percent 

of the children of wives who were not employed 

were classified as low-birth-weight babies. The 

lower average birth weight of babies born to 

employed wives was due to fewer babies ofhigh 

birth weight rather than to more babies of low 

birth weight. Employed wives had fewer babiesof 

both low and high birth weights and more in the 

3,001 -3,500 gram class (fig. 1). Thehighconcentration of birth weights of babies of employed 

wives in the modal interval was apparent foreach 

age category except that ofunder 20years. Among 

these young wives the distributions were essentially the same both for those who wereemployed 

daring pregnancy and those who were not. 

The lower average birth weight of children 

of married women who were employed during 

pregnancy was found only among white wives. 
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50 

= Not employed 43.7 

~ Employed 40 

1- 30 I Z 

u 

: 

: 20 

10 8.4 7.0 

0 lla 

2,500 grams 2,501- 3,001- 3,301- 4,001 grams 

and under 3,000 3500 4,000 and over 

Figure 1. Percent distribution of babies by birth-


weight intervals according to mother!s employment


status during pregnancy.


Among babies born to white mothers there was a 

difference of 50 grams in the average birth weight; 

3,310 grams for babies of mothers who were not 

employed, 3,260 grams for babies of employed 

mothers (table C). However, for babies of nonwhite mothers the reverse situation was found. 

The babies of nonwhite mothers who were not 

employed during pregnancy weighed, on the 

average, 3,110 grams, and the babies of nonwhite 

mothers who were employed weighed, on the 

average, 3,190 grams. Thus, children of working 

nonwhite mothers averaged 80 grams heavier than 

the children of nonwhite mothers who were not 

employed. Further, 13.0 percent of the nonwhite 

mothers who were not employed during pregnancy 

had babies who weighed 2,500 grams or less, 

while only 9.7 percent of those who were employed 

had babies so classified (table 4). 

The birth weights by the trimester of pregnancy when the mother was last employed show 

an interesting pattern. The average birth weight 

was lower and the percentage weighing 2,500 

grams or less was higher for babies of mothers 

who stopped working during the second trimester 

than of those who stopped in the first trimester 

or who were still working during the third trimester. This is quite possibly the result of selection on the part of the attending physician. If the 

mother was having medical problems he might 

advise her to stop working if all was going well 

medically, she might continue. 

In conclusion, there is no evidence here that 

working during pregnancy increased the risk of 

having a low-birth-weight baby. On the contrary, 

except possibly for pregnant women under 20, the 

reverse seems to be true, particularly for the 

ncmwhite woman who was employed. 

Family Income 

A second factor which might be expected to 

influence the weight of the newborn is the income 

of the family into which it is born. The influence 

of income would not be directly on the weight, 

but on diet and medical care both of which might 

influence weight and are dependent upon adequate 

financial resources. 

The income referred to in this report is the 

total money income during the previous calendar 

year of all members of the family who were usual 

residents of the household at the time of the 

child’s birth. In the case of couples whose marriage took place in 1963 and who were not a 

family in 1962, their individual incomes, if any, 

were added and used as a family income. 

Table C. Average birth weight and percent 

of babies weighing 2,500 grams or less, 

bv color of mother and employment status 

d~ing pregnancy: Uni.te~ States, 1963 

legitimate live births 

Color of mother and 

employment status 

during pregnancy 

White 

Not employed 

Employ Ed--------------

Nonwhite 

Not employ Ed----------

Employed 

Percent 

Average of 

birth babies 

weight 2,500 

in grams grams 

or less 

3,300 6.5 

3>310 6.8 

3,260 6.0 

3,’130 11.8 

3,110 13.0 

3,190 9.7 

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Table D. Average birth weight, by color and percent of births to white wives according 

to 1962 family income: United Stat-es, 1963 legitimate live births 

1962 family income 

All incomes 

Under $3,000----------------------------------------

$3,ooo-$4,999---------------------------------------

$5,OOO-$6,999---------------------------------------

$7,000 and over 

The average birth weight was higher ineach 

succeeding income class as shown in table D. 

Children born into families with a 1962 incomeof 

less than $3,000 weighed, on the average, 3,180 

grams; children born into families with a 1962 

income of $7,000 or over weighed 3,330 grams. 

Simultaneously, the percentage of low-birthweight babies declined from 10.4percentforthose 

with a family income of less than $3,000 to 5.5 

percent where the family income was$7,0000r 

morein 1962 (table 5). 

Within each of the income classes, the 

average birth weight of babies borntowhitewives 

was higher than that of babies born to nonwhite 

wives. The decreased proportion of nonwhite 

births in each succeeding income class accounts 

for part of the increased birth weight whenbirths 

to all married women are considered. However, 

the average birth weight washigherti the higher 

income classes for both white and nonwhite sothe 

increase in birth weight with increased incomeis 

independent of color. 

Table 5 shows moredetailfor income classes 

for each color than table D. However, there are 

so few nonwhite mothers in the higher income 

classes that the sampling error is too high to 

show them separately. It is therefore possibleto 

show only all married women and white married 

women, bearing in mind that in the upper income 

classes almost all the women were white. 

Average birth weight 

in grams 

All White Nonwhite wives 

+ 

3,280 3,300 I 3,130 

I 

3,180 3,200 3,080 

3,280 3,300 3,160 

3,310 3,310 3,300 

3,330 3,330 3,190 

Percent 

of 

births 

to 

white 

wives 

87.3 

69.6 

85.3 

95.2 

96.5 

Among white wives then, the average birth 

weight of their children was higher for each income class until the $10,OOO level. The average 

weight in the class $10,000 and over was somewhat lower than in the $7,000-$9,999 class, but 

the difference was too small to have any statistical significance. The percentage of babies 

weighing 2,500 grams or less was somewhat 

higher and the percentage weighing 3,501 grams 

or over was somewhat lower in the highest income group than in the $7,000-$9,999 class. Itis 

possible that the shift toward lower birth weights 

in the topincome groupis related toan increased 

proportion of women aged 35 and over in that 

group. As previously noted, data from this survey 

show a lower average birth weight for babies 

born to these women. 

This possibility is supported by data shown 

in table 6. For each of the three lower income 

classes the modal age class is 20-24 years. For 

the income class $7,000 and over the modal age 

class is 25-29 and there were about twice as 

many women aged 35 or older as in any of the 

three lower income classes. In addition, approximately 40 percent of the women aged 350r older 

were members of families with a 1962 income of 

$7,000 or more. 

Within each age class, except 35 and over, 

the pattern consisted of higher average birth 

weights in families with higher incomes. The 

6 
pattern shows slight variations and the differences 

between incomes classes are often not statistically significant, but the pattern seems to be 

consistent enough to say that the family income 

does exert an effect on birth weight which is independent of the wife’s age. 

Since a low family income appears to exert 

a depressing effect on the weight at birth, resulting in a lower average birth weight and a higher 

percentage of babies weighing 2,500 grams or less 

in the low income classes, and a mother’s employment during her pregnancy seems mainly to 

result in a concentrated range of birth weights, 

it seems advisable to look at employment within 

each income class. These data are shown in 

table 7. 

In families with an income of less than $3,000 

in 1962 there was no difference in the average 

birth weight between babies of mothers who were 

employed during pregnancy and those who were 

not. In each income class above $3,000 there was 

a difference of 40-80 grams in the average weight, 

with the babies of employed wives weighing somewhat less than those born to wives who were not 

employed. However, except for the class $3,000-

$4,999, the employed wives had fewer babies 

weighing 2,500 grams or less than the wives who 

were not employed. Within each income class 

there was a higher concentration of birth weights 

in the modal class of 3,001-3,500 grams for babies 

born to employed wives than for babies born to 

wives who were not employed. 

Finally, both among wives who were employed 

during pregnancy and for those who were not, the 

average birth weight was higher as the family’s 

income was higher. The percentage of babies who 

weighed 2,500 grams or less decreased as the 

family’s income increased from under $3,000 to 

$10,000. 

Visits for Medical Care During Year 

Before Childbirth 

Due to the structure of the questionnaire 

used in the 1963 National Natality Survey, it is 

impossible to separate the visits for prenatal 

care from visits for other kinds of medical care. 

It is necessary to include all visits to physicians 

or to medical facilities during the entire 12-month 

period before the baby was born. The advantages 

and disadvantages of the 12-month period, the 

methods used to collect the information about the 

date of the first visit and the number of visits, 

and an analysis of the data have all been presented 

in a previous report in this series.2 The reader 

who is interested in the details should consult 

that report in addition to the technical appendixes 

at the end of this report. 

However, a few points should be stated here. 

First, the collection of information on visits for 

medical care was relatively independent of the 

mother. The mothers’ responses served only to 

double check so that no source of care was missed. 

Second, the information on the date of first visit 

and the number of visits cam~ directly from the 

physician or the medical facility providing the 

care. Response rates were excellent. Ninetythree percent of the physicians and 98 percent of 

the medical facilities responded to the questionnaires. Furthermore, almost all of the returned 

questionnaires were complete in all details. 

Finally, since it was impossible to ascertain 

when the first visit for prenatal care took place, 

the mothers who first saw a physician or were 

seen at a medical facility during the three months 

before conception are shown together with the 

mothers who first received care during the first 

three months of pregnancy and the assumption 

was made that those who were receiving medical 

care before conception continued to do so afterwards. This assumption is justified by the fact 

that women whose first medical care during the 

year was before conception made more visits on 

the average than women whose first medical care 

during the year was after conception. 

Table E shows the average birth weight and 

the percent of births weighing 2,500 grams or less 

according to the trimester of the first visit. Table 

8 shows the complete percent distribution by 

birth-weight intervals. 

For all legitimate births, babies born to 

married women who were receiving medical care 

before the end of the first trimester of pregnancy 

were heavier than babies whose mothers did not 

receive care until later in pregnancy. Moreover, 

the later in pregnancy that care began, the higher 

the percentage of babies weighing 2,500 grams or 

less. 

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Table E. Average birth weight and percent of babies weighing 2,500 grams or less, by 

color: United States, 1963 legitimate live births 

All wives White Nonwhite 

Trimester 

for 

of first visit 

-inedical care Average 

birth 

Percent 

of 

births 

Average 

birth 

Percent 

of 

births 

Average 

birth 

Percent 

of 

births 

weight 2,500 weight 2,500 weight 2,500 

in grams grams in grams grams in grams grams 

or less or less or less 

All trimesters 3,300 6.5 

First 3,300 3,310 6.1 3,090 13.9 

Second 3,230 ?:; 3,250 6.8 3,110 11.1 

Third 3,250 3,280 3, L40 11.2 

No care 3,250 1!:$ 3,160 1<:: 3,370 9.5 

According to the datapresentedin column20f 

table E there appearstobeanincreasein the proportion of low birth weight babies of approximately 

one percent with each trimesterthatmedicalcare 

was delayed. Among women whose first visit for 

medical care was before the end of the first mimester, approximately 6.7 percent of the births 

weighed 2,500 grams or less. Among thosewhose 

first medical care was in the third trimester, 

approximately 8.6 percent of the births weighed 

2,500 gramsor less. 

However, the differences in birth weight 

according to the trimester of first medical care 

are not the same for the white and nonwhite 

wives. The percentage of babies weighing 2,500 

grams or less who were born to white mothers 

was 6.1 for those receiving care beforetheendof 

the first trimester of pregnancy; 6.8 for those 

who first received care in the second trimester; 

7.8 for those who first received care in the third 

trimester; and 13.0 for those who received no 

medical care before the birth. No medical care 

was reported for only an estimated46 thousand 

married white women, 1.4 percent, but these 

mothers had 2.8 percent of the low-birth-weight 

babies, Despite the small number of mothers 

receiving no care, the difference between their 

rate of having babies weighing 2,500 grams or 

less and that for mothers receiving any careis 

statistically significant. 

Among nonwhite married women, the base 

numbers are too small for differences to have any 

statistical significance, but the trend is in the 

opposite direction. ” Babies born to nonwhite 

mothers who received medical care before the 

end of the first trimester had a lower average 

birth weight and a higher incidence of low birth 

weight than babies born to any group of wives 

which started care later. Those wives who had 

no prenatal care, as defined for this survey, had 

on the average the heaviest babies and the fewest 

babies of low birth weight. 

Although there are no data from this survey 

to test any hypothesis about the inverse relationship between timing of medical care and birth 

weight among the nonwhite wives, indirect information offers some possible explanations. First, 

there was a relationship between level of income 

and medical care2 and the nonwhite mothers were 

almost all in the lower income groups. It is possible that only those nonwhite women who were in 

obvious need of medical care sought it early in 

pregnancy or even before pregnancy began and 

that conditions which led them to seek care were 

also condition’s which predisposed them to have 

either premature or low-birth-weight babies. 

Support for this possibility is found later in this 

report in the section on income and trimester of 

care. Second, the women who were reported as 

receiving no care may have received care from 
------------------------

-------------------------------- ------------------------------

------------------------------ ----------------------------

---------------------------- -----------------------

------------------------------ -----------------------

midwives who were not defined in this survey as 

sources of medical care. It is knowm from registration data that although only 1.6 percent of all 

live births in the United States were attended by 

midwives in 1964, 8.0 percent of nonwhite births 

in the United States and 17.9 percent of nonwhite 

births in the South had midwives recorded as the 

attendant at birth. 1 

A second measure of medical care was the 

number of visits made during the year. With the 

exception of the nonwhite mothers who received 

no care, the average birth weight increased as the 

amount of care increased from no visits to 15-19 

visits (table 9). The percentage of babies who 

were of low birth weight showed a general decline 

through this same range. 

There was a slight but not significant decrease in the weight of babies born to mothers 

who had made 20 visits or more for medical care. 

It is possible that the women who made 20 visits 

or more were women who had medical problems 

in their pregnancies which would lead to lower 

birth weights. The same nonsignificant decline 

has already been noted in the top income and age 

groups. 

There is a distinct difference in both the 

average weight and the percentage weighing 2,500 

grams or less between babies born to mothers 

who made fewer than 10 visits and those born to 

mothers who made 10 visits or more. When the 

mother made fewer than 10 visits, the average 

weight was less than 3,200 grams and 10.5 percent of the babies were of low birth weight. When 

the mother made 10 visits or more, the average 

weight was over 3,300 grams and only 5.2 percent 

of the babies weighed 2,500 grams or less. Approximately twice as many low-birth-weight 

babies were born to women making fewer than 10 

visits as were born to women making 10 visits 

or more. In addition the average birth weight was 

150 grams less for the women making fewer than 

10 visits (table F). 

Table 11 shows the birth weight dist~ibution 

according to the trimester in which the mother 

first received care and whether she made fewer 

or more than 10 visits. Regardless of when the 

first visit was made, the mothers who made 10 

visits or more had fewer low-birth-weight babies 

than those who made fewer than 10 visits. For 

example, among women whose first visit for 

medical care was during the second trimester of 

pregnancy, 11 percent of those who made fewer 

than 10 visits had low-birth-weight babies while 

only 4 percent of those who made 10 visits or 

Table F. Average birth weight according to 1962 family income, by number of visits fOr 

medical care during 12 months before childbirth:United States, 1963 legitimate — live

births


1962 family income 

Number of visits 

All Under $3,000- $5,000- incomes $3,000 $4,999 $6,999 a!;’ Z% 

Average birth weight in grams


All visits 3,280 3,310 3,330 

====+== 

O visits 3,250 3,420 3,150 .~ ;!; 

1-4 visits 3,170 3,130 3,150 3,160 3,280 

5-9 visits 3,200 3,120 3,220 3,220 3,260 

10-14 visits 3,310 3,230 3,330 3,360 3,300 

15-19 visits 3,360 3,230 3,320 3,390 3,430 

20 visits or more 3,350 3,200 3,440 3,330 3,340 

O-9 visits 3,190 3,180 3,270 

10 visits or more 3,350 3,360 3,350 

9

more had low-birth-weight babies. The difference 

in the average birth weight was 160 grams. 

Since birth weights were higher in the upper 

income classes and among mothers receiving 

earlier or more medical care, and since the 

amount of medical care is related to the family’s 

income, the last two tables (11 and 12) are devoted to an examination of the variability in 

birth weight according to the amount of medical 

care within each of the income classes. 

In families with a 1962 income of less than 

$3,000, an inverse relationship was found between 

average birth weight and trimester of first 

medical care. Those mothers who received care 

late in pregnancy or who received no care had 

heavier babies on the average and had fewer lowbirth-weight babies than those who received care 

early in pregnancy. No relationship is evident 

between birth weight and the number of visits. It 

should be remembered that in this low income 

class approximately 30 percent of the women 

were nonwhite and among these women the highest 

average birth weights were found when there was 

the least medical care. 

In each of the three higher income classes 

the highest birth weights were found when medical 

care was begun before the end of the first trimester of pregnancy. However, the women in 

each income class who began their care earliest 

did not always have the lowest incidence of lowbirth-weight babies in their income class. 

If trimester of first medical care is treated 

as the major variable rather than income, that is, 

income classes within each trimester are compared, there is no clear pattern evident and 

certainly no statistical justification for stating 

that there are real differences. There may be an 

increase in birth weight with increased family 

income within each trimester of care classification, but the data have not been tabulated in a fashion which would permit the use of the refined statistical techniques necessary to support such a 

hypothesis. 

Table F shows the average birth weight for 

each income class when the mothers are also 

classified by the number of visits made during the 

year. Within each income class, there is a significant difference in weight between babies whose 

mothers made 5-9 visits and those whose mothers 

made 10-14 visits. In general, it can be said 

that mothers who made fewer than 10 visits 

(with the exception of those in families with a 1962 

income under $3,000 who received no care) had 

lighter babies than those who made 10 visits or 

more, regardless of the family’s income. Conversely, for mothers who made fewer than 10 

visits, the average birth weight was higher when 

the family’s income was greater; the same was 

also true for mothers who made 10 visits or more. 

Finally, within each income class there were more 

low-birth-weight babies born to mothers who 

made fewer than 10 visits than to mothers who 

made 10 visits or more (table 12). 

There is no explanation for the difference in 

birth weight between babies whose mothers made 

fewer than 10 visits and those with 10 or more 

available from the data in this survey. The 

information was collected after the birth had 

taken place and physicians and medical facilities 

were not asked to furnish any diagnostic information. It is possible that conditions outside the scope 

of the survey account for many of the differences 

observed between levels of medical care. Given 

the uniform availability of care it seems logical 

to assume that women with medical problems not 

directly related to pregnancy and women who 

were experiencing difficulty with the current 

pregnancy would both receive more medical 

attention than women without such problems. The 

women in each level of care category are almost 

certainly selected and are not randomly distributed. Without knowledge of the basis of selection, 

the data presented in this report have definite 

limitations and should be interpreted with caution. 

Ideally, statistics on women without complications of pregnancy should be shown separately 

from those on women with complications. However, unless such information is recorded accurately on the birth certificate, a special study has 

to be made in order to obtain the necessary data. 

This study was not designed for that purpose and 

so the statistics presented here only indicate 

possible differences and areas where more research is needed. 

10 
REFERENCES 

1

National Center for Health Statistics: Employment during 

pregnancy: United States, 1963 legitimate live births. Vital 

and Health Statistics. PHS Pub. No. 1000-Series 22-No. 7. 

Public Health Service. Washington. U.S. Government Printing 

Office, Sept. 1968. 

2

National Center for Health Statistics: Visits for medical 

and dental care during the year preceding childbirth: United 

States, 1963 births. Vital and Health Statistics. PHS Pub. 

No. 1000-Series 22-No. 4. Public Health Service. Washington. 

U.S. Government Printing Office, hiay 1968. 

3National Center for Health Statistics: h!ethods and response characteristics of the? fational Natality Survey, United 

Statee, 1963. Vital and Heatth Statistics. PHS Pub. No. 1000-

Series 22-No. 3. Washington. U.S. GovernmentPrinting Office, 

Sept. 1966. 

4~i~h > L-: Surt,ey SampZing. New York. John ~VileY ~ Sons, 

Inc., 1965. p. 559. 

5

National Center for Health Statistics: Vital Statistics of 

the United States, 1963, Vol. I. Public Health Service. Washington. U.S. Government Printing Office, 1964. 

6hlcCarthy, P. J., Simmons, W. R., and Losee, G. J.: Replication Techniques for Estimating Variant es From Complex 

Surveys. Paper presented at a joint session of the Epidemiology and Statistics Sections at the Nine@ -Third Meeting of 

the American Public Iiealth Association. Chicago, 111. Oct. 

18, 1965; and National Center for Health Statistics: Replication, an approach to the analysis of data from compIex surveys. Vital and Health Statistics. PHS Pub. No. 1000-Series 

2-No. 14. Public Health Service. Washington. U.S. Government Printing Office, Apr. 1966. 

000 

11

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Table 1.


2.


3.


4.


5.


6.


7.


8.


9.


10.


11.


12.


DETAILED TABLES 

Page


Average birth weight, number of “births,and percent distribution, by birth-weight


intervals according to age and color of mother: United States, 1963 legitimate


live births 13


Average birth weight,number of births, and percent distribution, by birth-weight


intervals according to live-birth order and color of mother: United States, 1963


legitimate live births 14


Average birth weight, number of births,and percent distribution, by birth-weight


intervals accordingto a e of mother and whether mother was employed during preg­


nancy: United States, 1863 legitimate live births 15


Average birth weight, number of births, and percent distribution by birth-weight


intervals according to color of mother and trimester of last employment during


pregnancy: United States, 1963 legitimate live births 16


Average birth weight, number of births,and percent distribution, by birth-weight


intervals according to family income in 1962 and color of mother: United States,


1963 legitimate live births 17


Average birth weight, number of births , and percent distribution,by birth-weight


intervals according to family income in 1962 and age of mother: United States,


1963 legitimate live births 18


Average birth weight, number of births,and percent distribution, by birth-weight 

intervals according to family income in 1962”and whether mother was employed 

during pregnancy: United States, 1963 legitimate live births 19 

Average birth weight,number of births , and percent distribution, by birth-weight


intervals according to trimester of first visit for medical care and color of


mother: United States, 1963 legitimate live births------------------------------ 20


Average birth weight, number of births,and percent distribution, by birth-weight


intervals according to number of visits for medical care and color of mother:


United States, 1963 legitimate live births 21


Average birth weight,nurnber of births , and percent distribution, by birth-weight


intervals according to trimester of first visit for medical care and number of


visits: United States, 1963 legitimate live births 22


Average birth weight, number of births,and percent distribution, by birth-weight


intervals according to family income in 1962 and trimester of first visit for


medical care: United States, 1963 legitimate live births 23


Average birth weight,number of births, and percent distribution, by birth-weight


intervals according to family income in 1962 and number of visits:United States,


1963 legitimate live births----------------------------------------------------- 24


12

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Table 1. Average birth weight, number of births, and percent distribution, by birth-weight inter­


vals according to age and color of mother: United States, 1963 legitimate live births


Birth weight


Average


Age and color birth Births 2,500 2,501- 3,001- 3,501- 4,001
 weight Total grams 3,000 3,500 4,000 grams


or less grams grams grams or more


Number


in
 All ages Grams thou- Percent distribution


sands


Total 3,280 3,797 100.0 7.2 19.4 39.2 26.1 8.0 

White 3,300 3,315 100.0 6.5 18.8 39.1 27.1 8.5 

Nonwhite 3,130 482 100.0 11.8 23.7 40.0 19.8 4.7 

Under 20 years 

Total 3,180 468 100.0 8.2 22.7 42.6 20.7 5.8 

White 3,210 407 100.0 6.9 21.3 43.6 22.0 6.3 

Nonwhite 2,990 60 100.0 17.5 32.1 36.0 11.8 2.6 

20-24 years 

Total 3,250 1,354 100.0 7.6 19.7 41.5 24.4 6.7 

White 3,270 1>197 100.0 6.7 19.3 41.1 25.6 7.2 

Nonwhite 3,050 156 100.0 14.3 22.9 44.7 15.2 2.9 

25-29 years 

Total 3,320 992 100.0 5.9 18.5 37.8 28.7 9.2 

White 3,330 861 100.0 5.6 18.0 37.4 29.2 9.9 

Nonwhite 3,210 131 100.0 8.0 21.8 40.8 24.9 4.6 

30-34 years 

Total 3,340 583 100.0 6.5 18.2 36.8 29.2 9.4 

White 3,350 505 100.0 6.2 17.3 36.9 29.6 10.1 

Nonwhite 3,230 78 100.0 8.4 24.1 36.1 26.5 4.9 

35 years and over 

Total 3,290 402 100.0 9.1 18.7 34.7 27.6 9.9 

White 3,300 345 100.0 8.6 18.4 34.7 28.8 9.5 

Nonwhite 3,210 57 100.0 12.2 20.4 34.7 20.4 12.2 

13

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Table 2. Average birth weight, number of births, and percent distribution, by birth-weight inter­


vals accordin~ to live-birth order and color of mother: United States, 1963 legitimate live


births


Birth weight


Live-birth order Average Births


and color birth 2,500 2,501- 3,001- 3,501- 4,001
 weight Iotal grams 3,000 3,500 4,000 grams


All live births


Total


White


Nonwhite


First birth


Total


White


Nonwhite


Second birth


Total


White


Nonwhite


Third birth


Total


White


N nwhite


+


Fourth birth or higher


Total


White


Nonwhite


or less grams grams grams or more


Number


in
 Grams thou- Percent distribution


sands


3,280 3,797 100.0 7.2 19.4 39.2 26.1 8.0 -

3,300 3,315 100.0 6.5 18.8 39.1 27.1 8.5


3,130 482 100.0 11.8 23.7 40.0 19.8 4.7


3,220 989 100.0 6.9 20.4 43.8 23.2 5.7


3,250 910 100.0 6.3 19.8 43.5 24.5 6.0


2,960 79 100.0 14.1 26.6 47.6 8.4 3.3


3,250 912 100.0 7.9 22.0 38.5 23.9 7.8


3,280 823 100.0 6.6 21.5 38.7 24.8 8.4 

2,990 89 100.0 19.9 25.8 36.5 16.2 1.7 

3,310 714 100.0 6.9 17.7 39.1 27.0 9.3 

3,320 639 100.0 6.3 17.6 38.1 28.1 9.9


3,150 74 100.0 11.3 18.6 48.4 16.8 4.9


3,320 1,182 100.0 7.2 17.7 36.1 29.8 9.2


3,340 943 100.0 6.9 16.3 36.0 30.8 10.0


3,240 240 LOO,. O
 8.1 23.5 36.2 25.9 6.3


—.


14

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Table 3. Average birth weight, number of births, and percent distribution, by birth-weight inter­


vals according to aze of mother and whether mother was employed during pregnancy:United States,


1963 legitimate liv~ births


Birth weight


Age and Average


birth Births employment status 2>500 2,501- 3,001- 3,501- 4,001
 weight Total grams 3,000 3,500 4,000 grams


or less grams grams grams or more


Numbez


All ages Gram in Percent distribution
 thou-


sands


L 

All mothers 3,280 3,79i 100.0 7.2 19.4 39.2 

Not employed 3,290 2,564 100.0 7.6 19.4 37.0 27.6 8.4 

Employed 3,250 1,179 100.0 6.5 19.5 43.7 23.2 7.0 

Under 20 years 

All mothers 3,180 8.2 22.7 42.6 20.7 5.8 

Not employed 3,180 287 100.0 8.2 22.7 43.1 20.6 5.4 

Employed 3,170 171 100.0 8.8 22.2 43.1 20.3 5.6 

20-24 years 

All mothers 3,250 1,354 100.0 7.6 19.7 41.5 24.4 6.7 

Not employed 3,250 833 100.0 7.8 19.8 40.5 24.8 7.1 

Employed 3,230 496 100.0 7.5 19.7 42.9 23.9 6.0 

25-29 years 

All mothers 3,320 5.9 18.5 37.8 28.7 9.2 4=’ 

Not employed------------------ 3,330 688 100.0 6.1 19.4 33.4 31.5 9.5 

Employed 3,290 294 100.0 5.2 16.6 46.9 22.9 8.4 

30-34 years 

All mothers 3,340 583 100.0 6.5 18.2 36.8 29.2 9.4 

Not employed 3,350 447 100.0 7.6 17.3 35.2 29.7 10.3 

+ 

Employed 3,320 133 100.0 2.2 21.1 42.2 28.2 6.4 

35 years and over 

AH mothers 3,290 4021 100.0 9.1 18.7 34.7 27.6 9.9 

Not employed 3,300 309 100.0 9.7 17.8 32.9 30.2 9.3 

Employed 3,230 85 100.0 7.7 21.4 40.8 18.5 11.6 

Unknown 

Total 3,300 55/ 100.0 3.5 20.9 45.8 18.4 11.3 

15

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Table 4. Average birth weight, number of births, and percent distribution, by birth-weight inter­


vals according to color of mother and trimester of last employment during pregnancy: United


States, 1963 legitimate live births


Birth weight


Color and Average


birth Births
 employment status weight Total grams 3,000 3,500 4,000 grams


2,500 2,501- 3,001- 3,501- 4,001


Total


All mothers


Not employed


Employed


First trimester-------------


Second trimester


Third trimester-------------


Unknown trimester


Employment unknown


White


All mothers


Not employed------------------


Employed


First trimester


Second trimester------------


Third trimester-------------


Unknown trimester


Employment unknown


Nonwhite


All mothers


Not employed------------------


Employed----------------------


First trimester-------------


Second trimester------------


Third trimester


Unknown trimester


Employment unknown


or less grams grams grams or more


Number


Grams thou- Percent distribution 

sands 

3,280 3,797 100.0 7.2 19.4 39.2 26.1 8.0 

3,290 2,564 100.0 7.6 19.4 37.0 27.6 8.4 

3,250 1,179 100.0 6.5 19.5 43.7 23.2 7.0 

3,270 165 100.0 5.8 20.2 44.4 19.9 9.6 

3,210 374 100.0 8.0 19.7 43.0 23.1 6.3 

3,280 555 100.0 5.6 18.9 43.5 25.1 6.8 

3,180 85 100.0 7.2 22.1 47.1 17.6 6.0 

3,300 55 100.0 3.5 20.9 45.8 18.4 11.3 

in


3,300 3,315 100.0 6.5 18.8 39.1 27.1 8.5 

3,310 2,248 100.0 6.8 18.5 37.0 28.7 9.0 

3,260 1,016 100.0 6.0 19.5 43.6 23.8 7.1 

3,260 147 100.0 5.9 20.8 45.6 17.6 10.1 

3,220 332 100.0 7.2 19.2 43.2 24.3 6.0 

3,300 469 100.0 5.2 18.5 42.9 26.1 7.2 

3,160 68 100.0 5.7 24.6 45.9 19.3 4.5 

3,320 51 100.0 3.8 20.3 43.9 19.8 12.2 

3,130 482 100.0 11.8 23.7 40.0 19.8 4.7 

3,110 316 100.0 13.0 25.5 37.4 20.3 3.8 

3,190 163 100.0 9.7 20.0 44.3 19.3 6.6 

>,< >,< .~ >k $< * $< * 

3,140 42 100.0 14.0 23.0 40.8 13.9 8.3 

3,180 86 100.0 7.9 21.0 46.7 19.6 4.8 

.* ;,< #r .k ;,< >? >’< * 

-k ;,< ;’< ;,{ * * * * 

16

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Table 5. Average birth weight, number of births, and percent distribution, by birth-weight inter­


vals according to family income in 1962 and color of mother:United States, 1963 legitimate live


births


Birth weight


1962 family income Average 

birth
 Births
 and color 2,500 2,501- 3,001- 3,501- 4,001
 weight Total grams 3,000 3,500 4,000 grams


All incomes


Total


White


Nonwhite


Under $3,000


Total


White


Nonwhite


$3,000-$4,999


Total


White


Nonwhite


$5,000-$6,999


Total


White


Nonwhite


$7,000 and over


Total


White


Nonwhite


$7,000-$9,999


Total


White


Nonwhite


$10,000 and over


Total


White


Nonwhite


Unknown


Total


White


Nonwhite


or less grams grams grams or more


Number


Grams thou- Percent distribution 

sands 

3,280 3,797 100.0 7.2 19.4 39.2 26.1 8.0 

3,300 3,315 100.0 6.5 18.8 39.1 27.1 8.5 

3,130 482 100.0 11.8 23.7 40.0 19.8 4.7 

in


3,180 819 100.0 10.4 21.6 39.2 23.2 5.6 

3,200 570 100.0 8.8 20.1 38.9 26.3 5.9 

3,080 249 100.0 14.0 25.0 39.8 16.2 5.0 

3,280 1,030 100.0 7.7 18.7 39.8 25.0 8.8 

3,300 879 100.0 6.9 18.2 40.2 25.0 9.7


3,160 151 100.0 12.4 21.7 37.1 24.8 3.9


3,310 920 100.0 5.7 18.1 39.6 28.2 8.4


3,310 876 100.0 6.0 17.8 39.1 28.4 8.6 

3,300 44 100.0 22.4 50.4 23.5 3.7 

3,330 973 100.0 5.5 19.6 38.0 28.4 8.6 

3,330 930 100.0 5.4 19.5 38.0 28.6 8.6 

3,190 34 100.0 9.6 23.3 37.6 21.6 7.9 

3,330 667 100.0 5.0 20.5 36.8 29.1 8.6 

3,340 645 100.0 4.8 20.3 36.9 29.1 8.8 

3,190 22 100.0 9.7 25.5 32.0 29.4 3.5 

3,310 306 100.0 6.8 17.6 40.6 26.6 8.5


3,320 294 100.0 6.7 17.5 40.3 27.4 8.2 

-k .:. .:. >’< .x .:. .:. .: 

3,300 55 100.0 3.5 20.9 45.8 18.4 11.3 

3,320 51 100.0 3.8 20.3 43.9 19.8 12.2 

-k -k .:. .A- -:. -k -2 -2 

17

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Table 6. Average birth weight, number of bir~hs, and percent distribution, by birth-weight inter­


vals according to family income in 1962 and age of mother: United States, 1963 legitimate live


births


Birth weight


1962 family income Average 

birth
 3irths
 and age 2,500 2,501- 3,001- 3,501- 4,001
 weight Total grams 3,000 3,500 4,000 grams


or less grams grams grams or more


I


Vumber


All incomes Grams Percent distribution
 th%­


~ands


All ages 3,280 3,797 100.0 7.2 19.4 39.2 26.1 8.0 — 

Under 20 years 

20-24 years 

25-29 Years-------------------

30-34 jears 

3,180 

3,250 

3,320 

3,340 

468 

1,354 

992 

583 

100.0 

100.0 

100.0 

100.0 

;.; 

5:9 

6.5 

22.7 

19.7 

18.5 

I-8.2 

42.6 

41.5 

37.8 

36.8 

20.7 

24.4 

28.7 

29.2 

5.8 

::; 

9.4 

35 years and over 3,290 402 100.0 9.1 18.7 34.7 27.6 9.9 

Under $3,000 

All ages 3,180 819 100.0 10.4 21.6 39.2 23.2 5.6 

Under’20 years 3,110 221 100.0 10.9 24.4 42.4 18.5


20-24 years 3,170 309 100.0 10.6 19.9 41.4 24.3


25-29 years 3,210 135 10LO 11.1 20.3 37.7 22.5


30-34 years 3,260 81 100.0 11.1 20.7 32.4 27.2


35 years and over 3,300 73 100.0 6.1 23.6 30.3 29.4


$3,000-$4,999


All ages 3,280 1,030 100.0 7.7 18.7 39.8 25.0 

Under 20 years 

20-24 years 

3,230 

3,260 

156 

426 

100.0 

100.0 

6.9 

7.8 

21.4 

18.8 

42.6 

43.0 

21.9 

22.4 2? 

25-29 years-------------------

30-34 years 

3,290 

3,340 

252 

123 

100.0 

100.0 H 

17.6 

19.6 

37.7 

34.9 

29.7 

25.0 1;:: 35 years and over------------- 3,310 72 100.0 11.4 14.8 30.5 30.3 13.0 

$5,000-$6,999


All ages 3,310 920 100.0 5.7 18.1 39.6 28.2 8.4 

Under 20 years 3,210 100.0 4.9 24.4 43.0 19.6 8.1 

20-24 years 3,270 3:: 100.0 6.5 19.5 40.4 26.0 

25-29 years 3,360 276 100.0 3.8 17.2 36.5 32.9 u 

30-34 years 3,330 1;; 100.0 15.3 41.1 30.3 

35 years and over 3,310 100.0 u 15.6 41.7 23.6 1::: 

$7,000 and over 

All ages 3,330 973 100.0 5.5 19.6 38.0 28.3 8.6 

Under 20 years 3,370 24 100.0 4.1 52.9 31.8 3.3 

20-24 years 3,280 250 100.0 2!:; 40.1 26.1 6.8 

25-29 years 3,360 317 100.0 H 19.8 38.0 27.7 10.4 

30-34 veals 3,370 219 100.0 4.4 18.4 36.4 31.8 9.1 

35 yea;s and over 3,260 163 100.0 10.2 19.6 34.6 28.0 7.6 

Unknown


All ages 3,300 55 100.0 3.5 20.9 45.8 18.4 11.3


18

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Table 7. Average birth weight, number of births, and percent distribution, by birth-weight inter­


vals according to family income in 1962 and whether mother was employed during pregnancy:United


States, 1963 legitimate live births


Birth weight


A~=~~
 1962 family income and Births
 employment status weight 2,500 2,501- 3,001- 3,501- 4,001


Total grams 3,000 3,500 4,000 grams


or less grams grams grams or more


Number


All incomes Grams in Percent distribution
 thou-


sands


Total 3,280 3,797 100.0 7.2 19.4 39.2	 26.1 8.0 _ 

Not employed 3,290 2,564 100.0 19.4 37.0 27.6 8.4


Employed---------------------- 3,250 1,179 100.0 i:; 19.5 43.7 23.2 7.0


Under $3,000


Total 3,180 819 100.0 10.4 21.6 39.2 23.2 5.6


Not employed------------------ 3,180 598 100.0 11.1 21.3 37.7 24.4 5.5 

Employed 3,180 221 100.0 8.6 22.4 43.2 20.0 5.9 

$3,000-$4,999


Total 3,280 1,030 100.0 7.7 18.7 39.8 25.0 8.8 

Not employed 3,290 726 100.0 7.2 18.8 39.0 25.8 9.3 

Employed 3,230 304 100.0 9.1 18.4 41.8 23.0 7.8 

$5,000-$6,999


Total 3,310 920 100.0 5.7 18.1 39.6 28.2 8.4 

Not employed------------------ 3,320 628 100.0 18.7 36.8 29.7 8.7 

Employed 3,280 292 100.0 16.6 45.8 24.9 7.8 

$7,000 and over


Total 3,330 973 100.0 19.6 38.0 28.3 8.6


Not employed 3,360 612 100.0 18.7 34.4 30.9 9.8


Employed 3,280 361 100.0 21.1 44.0 24.0 6.4


$7,000-$9,999


Total 3,330 667 100.0 20.5 36.8 29.1 8.6


Not employed 3>360 420 100.0 19.8 33.6 31.2 10.0 

Employed 3,280 246 100.0 21.8 42.3 25.7 6.2 

$10,000 and over


Total 3,310 306 100.0 17.6 40.6 26.6 8.5


Not employed 3,340 191 100.0 16.3 36.2 30.3 9.5 

Employed 3,260 115 100.0 H 19.8 47.7 20.5 6.8 

Unknown


Total 3,300 55 100.0 3.5 20.9 45.8 18.4 11.3


19

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Table 8. Average birth weight, number of births, and percent distribution, by birth-weight inter­


vals according to trimester of first visit for medical care and color of mother: United States,


1963 legitimate live births


Birth weight


Trimester of first visit Average


and color birth Births 2,500 2,501- 3,001- 3,501- 4,001
 weight Total grams 3,000 3,500 4,000 grams


or less grams grams grams ‘or more


Number


in
 All trimesters Grams Percent distribution
 thou-


sands


Total 3,280 3,797 100.0 7.2 19.4 39.2 26.1 8.0 

White 3,300 3,315 100.0 6.5 18.8 39.1 27.1 8.5 

Nonwhite 3,130 482 100.0 11.8 23.7 40.0 19.8 4.7 

First trimester 

Total 3,300 2,246 Loo.o 6.7 18.2 39.4 27.2 8.5 

White 3,310 2,069 LOO.O 6.1 17.7 39.4 27.9 8.8 

Nonwhite 3,090 L77 LOO.O 13.9 23.8 39.4 18.5 4.4 

Second trimester


Total 3,230 724 100.0 7.5 20.4 41.7 23.9 6.6


White 3,250 611 100.0 6.8 20.1 41.4 24.0 7.7


Nonwhite 3,110 113 100.0 11.1 22.1 43.1 23.0 0.7


Third trimester


Total 3,250 679 100.0 8.6 23.2 35.3 25.8 7.2


White 3,280 531 100.0 7.% 21.8 34.3 29.0 7.1


Nonwhite 3,140 148 100.0 11.2- 28.2 38.9 14.2 7.5


No prenatal care


Total 3,250 79 100.0 11.5 12.0 41.9 24.1 10.5


White 3,160 46 100.0 13.0 15.3 49.4 10.9 11.3 

Nonwhite 3,370 33 LOO.O 9.5 7.2 31.4 42.6 9.3 

Unknown


Total 3,370 69 LOO.O 1.7 21.0 44.6 21.3 11.5


White 3,390 58 LOO.O 2.0 19.8 42.0 22.4 13.7 

Nonwhite * -2 $C >’< >k * >’< Ye 

20

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Table 9. Average birth weight, number of births, and percent distribution,by birth-weightinter­


vals according to number of visits for medical care and color of mother: United States, 1963


legitimate Iiv= births


Birth weight


Number of visits kverage II I I i I


and color birth Births 2,500 2,501- 3,001- 3,501- 4,001
 aeight Total grams 3,000 3,500 4,000 grams
 or less grams grams grams or more


Numbex 

All visits Grams th%- Percent distribution 

sands 

Total 3,280 3,797 100.( 7.2 19.4 39.2 26.1 8.0 

White------------------------- Nonwhite 

3,300 

3,130 

3,315 

482 

100.(

100.( 

6.5 

11.8 

18.8 

23.7 

39.1 

40.0 

27.1 

19.8 ;;; 

No visits 

Total 3,250 79 100.( 11.5 12.0 41.9 24.1 10.5 

White 

Nonwhite 

3,160 

3,370 

46 

33 

100.(

100.( 

13.0 

9.5 

15.3 

7.2 

&9.4 

31.4 

10.9 

42.6 

11.3 

9.3 

1-4 visits


Total------------------- 3,170 678 100.C 10.2 26.0 34.8 22.7 6.3


White 3,210 523 100.C 23.9 34.8 25.3


Nonwhite 3,040 155 100.C 12: 32.8 34.9 14.0


5-9 visits


Total 3,200 699 100.C 10.6 19.5 39.5 24..5


White------------------------- 3,210 557 100.C 9.6 19.6 39.7 25.1 

Nonwhite 3,150 142 100.c 14.5 19.0 38.6 22.3 ::: 

10-14 visits


Total------------------- 3,310 1,132 100.0 5.6 19.2 38.9 28.4 7.9


White------------------------- 3,320 1,054 100.0 5.3 18.8 38.5 29.2 8.2 

Nonwhite 3,130 78 100.0 9.9 24.0 44.8 17.7 3.6 

15-19 visits 

Total------------------- 3,360 697 100.0 3.9 17.3 42.1 26.7 10.1 

White 3,370 657 100.0 3.7 17.5 41.8 26.6 1;.: 

Nonwhite 3,260 41 100.0 6.1 14.1 47.0 28.2 . 

20 or more visits 

Total 3,350 430 100.0 6.1 14.0 41.4 28.2 10.3 

White 3,360 407 100.0 13.4 40.3 29.4 10.7 

Nonwhite 3,140 23 Loo. o ::? 23.9 60.5 8.2 3.3 

Unknown


Total------------------- 3,310 83 LOO.O 5.2 22.4 39.9 22.9 9.6


White 3,330 LOO.O 59 20.3 38.1 24.9
 .:.
 Nonwhite * .2 .:. -k -2 .L. 10.9


21

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Table 10. Average birth weight,number of births, and percent distribution, by birth-weight inter­


vals according to trimester of first visit for medical care and number of visits:United States,


1963 legitimate live births


Birth weight


Trimester of first visit Average


birth Births
 and number of visits 2,500 2,501- 3,001- 3,501- 4,001
 weight Tota1 grams 3,000 3,500 4,000 grams
 or less grams grams grams or more


Number


All trimesters Grams in Percent distribution
 thou-


sands


All visits 3,280 3,797 100.0 7.2 19.5 39.3 26.2 8.0


No visits 3,250 79 100.0 11.5 12.0 41.9 24.1 10.5 

1-9 visits 3,180 1,377 100.0 10.5 22.7 37.3 23.7 6.1 

10 or more visits 3,330 2,258 100,0 5.2 17.6 40.4 27.9 9.0 

Unknown 3,310 83 100.0 5.2 22.7 40.3 23.2 9.7 

First trimester


All visits 3,300 2,246 100.0 6.7 18.2 39.4 27.2 8.5


1-9 visits 3,140 40 100.0 12.7 21.4 37.5 22.6 5.8 

10 or more visits------------- 3,330 1,835 100.0 5.3 17.6 40.0 28.2 9.1 

Unknown----------------------- * * $< * * -k * * 

Second trimester


All visits 3,230 724 100.0 7.5 20.4 41.7 23.9 6.6


1-9 visits 3,150 363 100.0 11.0 21.1 41.0 22.1 5.5 

10 or more visits 3,310 359 100.0 4.0 19.4 42.8 26.0 7.8 

Unknown .~ J< * * -k * * >’< 

Third trimester


All visits 3,250 679 LOO.O 8.6 23.2 35.3 25.8 7.2


1-9 visits 3,230 612 LOO.O 24.6 34.9 25.4 6.7


10 or more visits------------- 3,410 62 LOO.O 9.8 38.9 30.6 12.9


* *
 Unknown * * * * 9<


Trimester unknown


Total 3,370 69 LOO.O 21.0 44.6 21.3 11.5


No prenatal care


Total 3,250 79 LOO.O 11.5 12.0 41.9 24.1 10.5


22

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Table 11. Average birth weight,number of births, and percent distribution, by bi:th-weight in:ervals according to family income in 1962 and trimester of first visit for med~cal care: Un~ted 

States, 1963 legitimate live births 

Birth weight


1962 family income and Lverage


birth Births trimester of first visit 2,500 2,501- 3,001- 3,501- 4,001
 veight Total grams 3,000 3,500 4,000 grams
 or less grams grams grams or more


Number


in
 All incomes Grams Percent distribution
 thou-


sands


All trimesters 3,280 “3,797 100.0 7.2 19.4 39.2 26.1 8.0 — 

First 3,300 2,246 100.0 6.7 18.2 39.4 27.2 8.5 

Second------------------------ 3,230 724 100.0 7.5 20.4 4L.7 23.9 6.6 

Third 3,250 679 100.0 8.6 23.2 35.3 25.8 

No prenatal care 3,250 79 100.0 11.5 12.0 41.9 24.1 1;:$ 

Trimester unknown 3,370 69 100.0 1.7 21.0 44.6 21.3 11.5 

Under $3,000 

All trimesters 3,180 819 100.0 10.4 21.6 39.2 23.2 5.6 

First 3,140 348 Loo.o 11.9 21.2 38.5 23.6 

Second------------------------ 3,160 212 100.0 1;.: 20.8 42.0 22.2 2:: 

Third 3,220 215 100.0 25.3 37.0 21.8 7.2 

No prenatal care 

Trimester unknown 

3,420

* 

35 

* 

100.0 

* 

5:9 

* 

10.4 

-2 

39.9 

* 

29.0 

* 

14.8 

* 

$3,000-$4,999


All trimesters 3,280 1,030 100.0 7.7 18.7 39.8 25.0 8.8 

First 3,310 562 100.0 6.7 17.7 39.8 26.0 9.8 

Second------------------------ 3,260 233 100.0 21.3 42.1 22.8 8.5 

Third 3,200 208 100.0 1;:: 19.2 38.0 24.7 5.8 

No prenatal care 

Trimester unknown 

3>150 

-2 

21 

* 

100.0 

-k 

17.8 

-2 

12.5 

-k 

33.0 

-2 

27.2 -:- 9.6 

-* 

$5,000-$6,999


All trimesters 3,310 920 100.0 5.7 18.1 39.6 28.2 8.4 

First 3,320 615 100.0 5.6 17.5 39.4 29.0 8.6 

Second 3,270 151 100.0 14.7 ;;.; 25.6 6.8 

Third 

No prenatal care 

Trimester unknown 

3,320

* 

* 

140 100.0 

-k .A. 

* -k 

::!-A. 

-k 

.A- 23.9 

-2 

..A. 

* 

29.3 

-2 

-:. 

9.3.A. 

* 

$7,000 and over


All trimesters 3,330 973 100.0 5.5 19.6 38.0 28.3 8.6


First 3,340 718 I.00.O 5.2 17.8 39.5 28.5 9.0


Second 3,260 126 LOO.O 6.4 24.4 35.1 26.9 7.1


Third 3,320 115 I-00.O 6.7 25.8 29.3 ;!: No prenatal care -2 -k -2
 ., J< -k .A- 30.9 7.3


Trimester unknown * * -k * .~. * .-b JA.


Unknown


Total 3,300 55 LOO.O 3.5 20.9 45.8 18.4 11.3


23

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Table 12. Average birth weight, number of births, and percent distribution, by birth-weight intervals


according to family income in 1962 and number of visits: United States, 1963 legitimate live births


Birth weight


1962 family income and Iverage 

Births
 number of visits birth 2,500 2,501- 3,001- 3,501- 4,001
 #eight Total grams 3,000 3,500 4,000 grams
 or less grams grams grams or more


I I 

Number 

All incomes Grams in 

thou- Percent distribution 

sands 

All visits-------------------- 3,280 3,797 100.0 7.2 19.4 39.2 26,1 8.0 — — 

No visits 3,250 100.0 11.5 12.0 41.9 24.1 10.5 

1-4 visits 3,170 6;; 100.0 10.2 26.0 34.8 22.7 6.3 

5-9 visits 3,200 699 100.0 10.6 19,5 39.5 24.5 5.9 

10-14 visits 3,310 1,132 100.0 5.6 19.2 38.9 28.4 

15-19 visits 

20 visits or more------------------- Unknown 

3,360 

3,350 

3,310 

697 

430 

83 

100.0 

100.0 

100.0 

3.9 

6.1 

5.2 

17.3 

14.0 

22,4 

42.1 

41.4 

39.9 

26.7 

28,2 

22.9 

1;:: 

10.3 

9.6 

Under $3,000


All visits 3,180 819 100.0 10.4 21.6 39.2 23.2 5.6 

No visits 

1-4 visits 

3,420 

3,130 

100.0 

2:; 100.0 12: 10.4 

26.1 

39.9 

34.7 

29.0 

20.5 

14.8 

5-9 visits 

10-14 visits 

3,120 

3,230 

203 100.0 

198 100.0 

13.7 

8.2 

20.0 

21.2 

:g.: 20.4 

28.5 N 

5.5 

15-19 visits 3,230 104 100.0 21.3 43:6 21.7 

20 visits or more------------------- Unknown 

3,200* 52 100.0 

?< .~ 1::: 

* 

15.4 

$< 

49.4;!c 23.4 

J< N * 

$3,000-$4,999


All visits 3,280 1,030 100.0 7.7 18.7 39.8 25.0 8.8 

No visits 

1-4 visits 

3,150 

3,150 

21 

206 

100.0 

100.0 

17.8 

11.0 

12.5 

23.0 

33.0 

40.1 

27.2 

21.3 R 

5-9 visits 3,220 225 100.0 20.4 37.2 27.4 6.1 

10-14 visits 3,330 284 100.0 H 16.4 43.5 26.3 8.6 

15-19 visits 3,320 174 100.0 20.6 40.4 20.0 12.4 

20 visits or more------------------- 3,440 112 100.0;!t H ;,c 10.9 35.5 31.8 16.3
 *
 Unknown J< * * 9< *


$5,000-$6,999


All visits 3,310 920 100.0 5.7 18.1 39.6 28.2 8.4


Unknown 

[0 visits 

-4 visits 

;-9 visits 

;!c 

3,160 

3,220 

11:100.: 

162 100.0 

.~ 

9.0 

8.4 

>’C 

29.2 

17.4 

;,< 

28.2 

43.8 

$< 

26,7 

26.1 

.0-14visits 3,360 313 100.0 5.0 17.6 36.6 30.8 

.5-19visits 3,390 193 100.0 2.1 14.2 44.7 29.5 

!0 visits or more------------------- Unknown 

3,330;,< 118 100.0 

>k 9< 

5.2 

-k 

16.1 

* 

43.2 

>? 

25.9 

* 

$7,000 and over 

All visits-------------------- 3,330 973 100.0 5.5 19.6 38.0 28.3 

No visits ;!< ;!< >“< >’C ;,< 

1-4 visits 

5-9 visits 

3,280 

3,260 

13: 100.: 

107 100.0 1::: 27.; 

20.2 

32.4 

32.8 

25.0 

24.6 1%: 

10-14 visits 3,300 335 100.0 4.8 21.8 38.7 28.0 6.7 

15-19 visits 3,430 225 100.0 15.7 40.1 31.9 1:.; 

20 visits or more------------------- 3,340 148 100.0 ::; 14.2 41.5 29.1 >.< 9< * 9< * * $C “,!<


Income unknown


Total------------------------- 3,300 55 100.0 3.5 20.9 45.8 18.4 11.3


24

APPENDIx I 

TECHNICAL NOTES ON METHODS 

Background of This Report 

This report presents estimates of the average birth 

weight and of the percent distribution of birthsby birthweight intervals for live births in 1963. It is basedon 

data collected in the 1963 National Natality Survey. The 

survey, which was conducted by the Division of Health 

Records Statistics of the National Center for Health 

Statistics (in part under contract with the Division of 

Radiological Health, Public Health Service), was designed primarily to provide national estimates of the 

amount and type of exposure to ionizing radiation experienced by women during pregnancy. In addition to 

obtaining radiation data from physicians and medical 

facilities, certain socioeconomic and demographic data 

which were thought to be relevant to the study were 

obtained from the mothers. 

Sources of Data 

The first source of data was the birth certificate. 

In addition survey procedures included a questionnaire 

mailed to each mother selected in the sample, to the 

attendant at birth, and to the hospital reported as the 

place of birth. These sources of information are identified on the birth record itself and are referred to as 

primary sources. 

Each of these primary sources was requested to 

identify other physicians, dentists, or medical facilities 

from whom the mother received any care during the 

year prior to the birth of her child. These additional 

sources of information are referred to as secondary 

sources. Questionnaires were also mailed to these secondary sources. Regardless of whether they were primary or secondary, the same information was obtained 

from all medical and dental sources. 

Information about the number of visits, the dates of 

the first and last visit, X-ray examinations, and other 

medical aspects was obtained only from physicians, 

medical facilities, and dentists. The medical section of 

the questionnaire sent to the mother was limited to 

identification of physicians and dentists from whom she 

received care. The mother was also requested to furnish 

certain socioeconomic and demographic information to 

supplement that recorded on the birth certificate. 

This report uses information obtained from three 

sources. Color, live-birth order, age of mother, birth 

weight, weeks of gestation, and legitimacy status were 

either recorded on the certificates or derived from entries on the certificates. Family income, employment 

during pregnancy, and names of sources of medical 

care was obtained from the questionnaire mailed to 

mothers of legitimate births. All information on the 

number of visits and the date of the first visit came 

from the questionnaire sent to physicians, hospitals, or 

clinics. Each physician, hospital, or clinic was also 

asked for names of other persons or facilities who 

might have furnished care to this mother and these 

additional sources of medical care were then sent 

questionnaires. 

Sample Design 

The sampling frame for the 1963 National Natality 

Survey was the file of microfilms of birth records received each month by the National Center for Health 

Statistics from the 54 birth registration areas of the 

United States. As a general rule, for each registration 

area these microfilm images are assigned a number 

prior to or during filming of the birth record. Each 

thousand consecutive images are defined as a “reel” 

and assigned a reel number starting from zero. Within each reel, the images are numbered from 1 to 1,000. 

The sampling for the survey was based on a probability design which made use of these preassigned reel 

and image numbers on the birth records. Each reel of 

the microfilm copies of the birth certificates constituted 

a primary sampling unit. Within each reel one record 

was chosen at random. Thus, a sample of 1 out of 1,000 

births was selected from the monthly shipment of records from the registration areas. 

The national sample included a total of 4,096 births 

for the year 1963. Of these 4,096 births, 214 were reported as illegitimate on the birth record. However, 

legitimacy is reported in only 35 of the 54 registration 

areas in the United States. Hence, a procedure was 

developed to infer legitimacy on the basis of indirect 

evidence on the birth certificate for the 19 registration 

areas not reporting this item. If the surname of the 

father on the birth record was different from the sur25 
----------------

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Table 1. Total number of births in the United 

States and the numberin the surveyof mothers: 

1963 National Natali.ty Survey 

I 

Item I Size 

I


Total count of births in the 

United States 4,098,000 

Number of births selected in the 

sample 4,096 

Number of births excluded from 

survey: 

Number of illegitimate births 316


Number of births from Missouri: 

July-December 1963--------------- 45 

Other 9 

Number of births included for the 

survey of mothers 3,726 

name of the child or if the surname of the father was 

not reported, the birth was imputed to be illegitimate. 

On the basis of this procedure, 102 births in the sample 

were inferred to be illegitimate in addition to those 

mentioned above. 

The mothers of these 316 illegitimate births plus 

the mothers of an additional W births were not queried. 

The State of Missouri withdrew from the survey after 

June 1963, so that the 45 births selected in the sample 

from Missouri for the period July through December 

1963 were excluded from the survey. Nine additional 

births were excluded from the survey either because 

residence was outside the United States or because no 

usable mailing address was available. Thus, the final 

sample of mothers to whom questionnaires were mailed 

was 3,726. Table I shows the size of the original sample 

drawn from the birth records and the final sample of 

mothers to whom questionnaires were mailed. 

In contrast with the survey of mothers, in which illegitimate birth s were excluded, medicalinquirie swere 

sent in all instances where a medical source of information was identified. Hence, statistics relating to 

medical care which did not require information provided by the mother were obtained for all births selected 

in the sample. 

The Birth Certificate and Questionnaires 

Facsimiles of the Standard Certificate of Live Birth 

andofthe questiomaireused in the survey are shownin 

appendix III. 

Although not all States use the standard certificate, 

most do include the basic information used in this report. The major exception is legitimacy (item 23) which 

is not reported in 19 States. The procedure which was 

developed to overcome this omission is discussed under 

sample design. 

The questionnaire sent tothe mother was designed 

primarily to obtain names and addresses ofanyphysicians and medical facilities which she visited during 

the year in addition to those named on the birth certificate. In addition, there were six questions concerning 

the family income during 1962 (the last calendar year 

before the birth), the educational attainment of the 

parents, the father’s employment status at the time of 

the birth, and the mother’s employment at any time 

during her pregnancy. 

The questionnaires sent to physicians and medical 

facilities were essentially alike. The respondent to this 

questionnaire was asked whether the mother had received any examination or treatment by X-ray during 

the 12 months preceding the birth of her child. If so, 

he was asked for details about the X-ray procedures. 

Whether the mother had receivedan X-rayexamination 

or not, the respondentwasaskedto reportthe numberof 

times the mother had been seen formedicalcare during 

the 12 months and the dates of the first and last visits 

during that period. 

The questionnaire sent to dentists was similar to 

that sent to physicians and medical facilities except that 

fewer questions were asked about the X-ray examinations. No information obtained from dentists is included 

in this report. 

Collection of Data 

Data for the 1963 National Natality Survey were 

collected primarily by mail. Using the addresses given 

on the birth certificate, questionnaires were sent to the 

mother, the physician who delivered the baby, and the 

medical facility where the baby was born, 

For these mothers, followup procedures consisted 

of a certified mailing 2 weeks after the initial mailing 

and a“ regular first-class mailing 3 weeks after the 

certified mail. Telephone or personal interviews were 

conducted by Bureau of the Census interviewers with 

mothers who did not respond after all three mailings 

and who lived in one of the field survey areas of the 

Current Population Survey program of the Bureau of 

the Census. These procedures resulted in a response 

rate of86.4 percent from mothers included in the survey (table II). 

Followup procedures for physicians, dentists, and 

institutions were similar to those for the mothers 

with two differences: (1) The first followup was by 

first class mail and the second followup was by certified mail. (2) Notelephone orpersonal interviews were 

conducted after the three mailings. The response rate 

from each of these sources washigher than90 percent. 

Reporting of visits to physicians andmedicalfacilities was relatively independent of the mother since 

the primary sources were narnedonthe birth certificate 

and the names of secandary sources were elicited on 

the questionnaire sent to the named sources. Comparison of the responses from the primary medical sources 

and from the mother showed that almost allthe secondary sources were named by primary sources and few 

26 
-----------------------------------------------

----------------------------------

------------------------------------

-------------------------------------

---------------------------------------

--------------------------------------------

Table 11. Response received from mothers, physicians, medical facilities, and dentists, by mail. 

ing waves: 1963 National Natality Survey 

I I I I 

Response status Mothers Physi- cians 

Medical facil- Dentists 

ities 

I I I I 

Total included in survey -------------------------------- 3,726 4,474 4,432 1,360 

Total response 

Response to original mail 

Response to second mail 

Response to third mail 

Response to interview 

Total nonresponse 

additional names were elicited from the mother query. 

However, it is possible that some sources of medical 

care were missed in the case of illegitimate births 

wherethem otherwas not queried. 

Processing of Data 

The completed questionnaires wereeditedand coded 

in accordance with predetermined specifications. The 

questionnaires were checked both for completenessand 

for consistency of response. If the reported data were 

inadequate for certain essential item~s, further mail 

inquiries were made to obtain them. 

After the edited andcodeddatahad beentranscribed 

onto punchcards the data were processed on electronic 

computers. The computer processing included consistency checks, interval edits, assignment of weights, and 

imputation for missing data.:] 

Nonresponse and Imputation of Missing Data 

Failure to obtain response represents one of the 

main sources of error ina survey, The extent of nonresponse and imputation of missing data in the 1963 

natality survey are discussed below. 

A total of 508 mothers, or 13.6 percent, had not 

responded after all followup procedures were completed. Included among the 508 are 2S respondents 

who returned the questionnaires substantially incomplete; for the purpose of processing the data, these 

respondents were treated in the same manner as the 

women who did not respond at all. A large proportion 

of this nonresponse was accounted for by mothers in 

the younger ages. Almost 57.6 percent of the 508 

mothers not responding, compared with 45.o percent 

Percent I 

86.4 I 93.1 [ 97.6 I 97.0 

I 

45.3 66.5 77.4/ 81.2 

29.0 17.6 15.3 11.5 

6.8 9.0 4.9 4.3 

5.1 . . . . . . . . . 

13.6 6.9 2.4 3.0 

I I I 

of the respondents, were less than 25 years of age 

(table HI). 

Besides these mothers who did not respond atall 

by mail or interview ~’unitnonresponser’), those who 

returned questionnaires but omlted part of the information also affect the quality of data derived from the 

survey. Nonresponse to item,s on questionnaires returned by mothers was minimal inmost instances and 

accounted for no more than 3.1 percent of the respondents for any single item. Table IV shows the percent 

not ascertained for specified items by age of mother 

and live-birth order. The principal problem ofincompleteness in the returned questionnaires arose from 

failure to obtain information about the total income of 

the family, a problem ivhich was found disproportionately among mothers under 25 years ofage and among 

mothers who were having their first birth or fifth or 

later birth. 

Statistics derived from the survey ofmothers were 

adjusted for unit nonresponse by imputing to nonratable III. Percent of respondents for whom 

specified items were not ascertained 

I 

Pert ent 

not Item ascertained 

27 
Table IV. Approximate standard errors for estimated numbers shown in this report 

Relative 

Size of estimate standard Standard 

error error 

25,000------------------ 16.8 4,200 

50,000------------------ 12.0 6,000 

75,000------------------ 9.8 7,350 

100,000------------------ 8,500 

250,000------------------ R 12,500 

500,000------------------ 3.3 16,500 

750,000------------------ 2.5 18,750 

1,000,000------------------ 20,000 

1,500,000------------------ ::; 22,500 

spondents the characteristics of sim,llar respondents. 

Similar respondents were mothers who responded to 

later mailings within each of the 24 age-of-mother, 

color, and live-birth-order groups. Two assumptions 

are inherent in this imputation procedure. First, the 

three birth record characteristics--age of mother, 

color, and live-birth order—which are available for 

responding as well as nonresponding mothers are related to the socioeconomic characteristics. Second, the 

nonrespondents are more like those who responded to 

the later mailings than those who responded to the 

first ms.il. The latter assumptionisbased onthe pattern 

of response by mailing wavesobservedinrelation to the 

educational and income level of the respondents. 

Thus, an array of known values was established 

in the computer using the respondents to later mailings 

within the 24 age, color, and birth-order groups as the 

population from which values were imputed to the nonrespondents. Values in the cells of the array were continually replaced by succesive known valuesas the file 

of records was processed; as a nonresponse record 

was read, values from the last known record in the 

appropriate cell of the array were imputed to the nonresponse record. 

Data are also adjusted for item nonresponse. Imputation procedures for missing data on questiomaires 

returned by mothers were based on the premise that 

“the presence of several correlated variables permits 

a reasonably good prediction of the missing variable. . . .“4 

Thus, missing data for items on employment of 

father, education of father, and fam:ly income were 

imputed on the computer on the sam: principle as for 

unit nonresponse, that is, imputation was made by assigning within homogeneous groups the characteristics 

of respondents to Iatermailings withknowndatam those 

respondents with missing data. Age, color, and birth 

order used for imputation of unit nonresponse was also 

used for imputation of missing data on employment of 

father. Missing information on education of father was 

imputed using age of father and education of mother. 

Missing information on family income was imputed usingage and education of father. 

Missing data on employment status of mother during 

pregnancy for three casesandonthe educationof mother 

for eight cases were imputed arbitrarily. 

Birth Records 

With the exception of color of child for births selected from New Jersey, age of father, and completed 

weeks of pregnancy, the information on the birth record was in most cases complete. During 1962the item 

on color of child was removed from the New Jersey 

birth record. Although this item was replaced in late 

1962, almost all births occurring during 1963 were 

registered on birth records not containing the question 

on color. Thus, informationon color ofchildwas missing on approximately 100 records from New Jersey 

selected in the sample. Imputation for color of child 

was carried out by means of a procedure using detailed 

geographic information on place of residence of mother 

and proportion of nonwhite population in that location 

accordingto the 1960 census. 

In addition, information on completed weeks of 

pregnancy was unknown on 214 birth records; number 

of previous fetal deaths was unknown for 92 records; 

and age of father was missing on 255 records. Imputation for these items was also carried out on the computerby substituting known values from the age, color, 

and birth-order array described earlier. Foritemssuch 

as birth weight, sex of child, and birthplace of mother, 

where the number of unknown cases was small, imputation was made arbitrarily. 

Physicians and Medical Facilities 

No imputation fornonresponse was undertaken for 

physicians and medical facilities because of the low 

nonresponse rate and the completeness of the information on the returned questionnaires. 

Estimation 

Statistics based on the survey areestimatesprepared by the use of a post-stratified ratio estimation 

procedure. The purpose of ratio estimation is to take 

into account available relevant information in the estimation process, thereby reducing the variability of the 

28

estimate. This procedure was carried out for each of 

the following 24 groups: 

Group Age Live-birth 

order 

White 

1 Under 20 years 1“ 

2 Under 20 years 2+ 

20-24 years 1 

; 20-24 years 2 

5 20-24 years 3-1-

6 25-29 years 

25-29 years ; 

; 25-29 years 3-4 

9 25-29 years 5i10 30-34 years 1-2 

11 

12 

30-34 years 

.30-34 years 

3-4 

5-1-

13 35 years or<rnore 1-4 

14 35 years or more 5+ 

Nonwhite 

:: Under 20 years 

Under 20 years L20-24 years 1-2 

:; 20-24 years 3-i19 25-29 years 1-2 

20 25-29 years 3-4 

21 25-29 years 5-1-

22 

23 

30-34 years 

30-34 years 

1-4 

5i24 35 years or more . ALL 

For each group, the ratio of tbenumber of births 

in the United States in 1963 (based on a 50-percent 

sample) to the number of births in the sample was determined.~llese 24 ratios comprised the sample 

weights used in estimating national totals for each of 

the 24 groups. The effect of this ratio adjustment was 

to make the estimates from the sample consistent with 

the count of births for each of the groups used inthe 

estj.tnation procedure. 

Thus, estimates of characteristics from the sample 

xmproduced using the following formula: 

x’=F2Ly 1=1 yi


where 

X’is the estimate ofthe numberof birthswithaparticz~ 

ular characteristic in group i, 

xi is the count of sample births with the characteristic 

in group i, 

Yi is the count of ~ SSJWIe births in group i, and 

Yi is tbetotalnutnber of births ingroupibased on the 

50-percent sample. 

Reliability of Estimates 

Since the statistics derived from this survey are 

estimates based on a sample, they may differ from the 

figures that wouId have been obtained hadacount ofall 

births in1963 been conducted using the same questionnaires and procedures. In additionto sampling errors, 

survey results are subject toerrors in conceptualformulation, ambiguities in definitions andinthe questionnaire construction, coding errors, biases due tononresponseor incomplete response, mistakesinediting,and 

tabulation errors. 

The probability design of the sample for the survey 

makes possible the calculation of sampIing errors.lle 

standard error is a measure of the sampling variation 

that occurs by chance because only a sample rather 

than theentire population is survey ed. The chances are 

about 68 out of 100 that an estimate from the sample 

differs from thevalue fortheentire population by less 

than the standard error. The chances are about 95 

out of 100 that the difference is less than twice the 

standard error. The standard error of a difference between two sample estimates isapproximately thesquare 

root of the sum of squares of each standard error considered separately. 

Estimates of sampling variability for the statistics 

derived from this survey were basedon 20 random halfsample replications. This technique yields overall variability through observation of variability among random 

subsamples of thetotal sample. Itreflectsboththe error 

that arises from sampling and apart of the measurement 

error, but it does not measure any systematic biases 

in the data. A general discussion of the development and 

evaluation of a replication technique for estimating 

variance has been published elsewhere.d However, the 

procedures and computations required to estimate variances by this method in the 1963 natality survey are 

briefly described below. 

For this survey, each record from the entire file 

of records was assigned systematically to a random 

group between 1 and 40. Twenty pairs of random groups 

were created from these groups. A half sample was 

formed by randomly selecting one group from each of 

the 20 pairs. This process was repeated until 20 “replicate half samples” were formed from which variance 

estimates were derived. The composition of the 20 

half samples was determined by an orthogonal plan. 

After the composition of each of the half samples 

was determined, all the estimation procedures used to 

produce the final estimates from the entire sample were 

applied separately to each of the resulting half samples. 

29 
-------

-------

-------

-------

----------------------------------------

----------------------------------------

----------------------------------------

----------------------------------------

----------------------------------------

Table	 V. Approximate standard error for estimated percents shown in this report 

Base of percent 

30,000-------

50,000------­

loo,ooo 

250jOO0 

5oo,ooo 

l,ooo,ooo 

2,000,000-------

3,000,000-------

4,000,000-------

Estimated percent 

ZElzEEE 

Standard error exDressed in 

percentage p~ints 

2.0 3.1 4.2 

1.5 2.4 3.3 

6.4 2$ 5.0 ;:: 

1.1 1.7 2.3 

0.7 1.1 1.5 

3.5 N 2.2 

3.8 

2.4 

0.5 0.7 1.0 1.4 1.6 1.7 

0.3 0.5 0.7 1.0 1.1 1.2 

0.2 0.4 0.7 0.8 0.9 

0.2 0.3 ;:2 0.6 0.6 0.7 

0.2 0.3 0.4 0.5 0.5 0.6 

An estimated variance S:, ofanestimated statistic 

x’ of the parameter X is obt;ined byapplyingthefollowing formula: 

where 

x’ is the estimate of Xbased on the entire sample, and 

x! is the estimate of Xbased on half sample i. 

Rules to determine the approximate standard errors 

for estimates presented in this report are as follows: 

1. Estimates ofaggvegates: Approximate standard 

errors of estimates of aggregates, such as the 

number of births with a given characteristic 

are given in table IV. 

2.	 Estimates of percentages in a pevcent distribution: Approximate standard errors forpercentages are determinedin one of the two following 

ways, depending upon the source of the base of 

thepercentaze: 

a.	 Where both numerator and denominator are 

estimates from the sample data, suchasthe 

percentage of employed wives whohadbabies weighing 2,500 grams orlessin 1963, 

the approximate standard errors are given 

in table V. 

b.	 Where the denominator is a value foundin 

one of the 24 ratio estimates cells shown on 

page 29and is therefore not subject tosampling error, the relative standard error of the 

percent is equivalent totherelative standard 

error of the numerator, which can be obtained from table N. 

3,	 .Estiwzatesof theaverage bivthweight: Approximate standard errors of theaverage birth weight 

are given in table VI. 

4.	 Difference between two sample estimates: The 

standard error of a difference isapproximately 

the square root of the sum of the squares of 

each standard error considered separately. 

This formula will represent the actual standard 

error quite accurately for the difference between separate and uncorrelated characteristics, although it is only a rough approximation 

in most cases. 

Rounding of Numbers 

The original tabulations on which the data in this 

report are based show figures to the nearest whole 

unit. In the published tables, estimates of aggregates 

are rounded to the nearest thousand although they are 

not necessarily accurate to that detail. Allpercentages, 

ratios, and averages were computed using unrounded 

figures. 

Table VI. Relative standard errors of average birth weigh~s as percent of the estimate, 1963 

Natality Survey 

Number of births in base 

Average birth weight 

50,000 100,000 250,000 500,000 1,000,000 

2,900 grams 1.43 1.15 1.12 1.06 .94 

3,000 grams 1.37 1.10 1.01 .93 .82 

3,100 grams 1.32 1.06 .90 .81 .78 

3,200 grams 1.24 1.03 .78 .69 .63 

3,300 grams 1.19 .98 .67 .56 .50 

000 

30 
APPENDIX II


DEFINITIONS OF CERTAIN TERMS USED IN THIS REPORT


Information From the Certificate 

of Live Birth 

Legitimacy status. —For States reporting legitimacy on the birth record, it is recorded from the entry 

on the birth certificate. For States not reporting legitimacy on the birth record, it is inferred from other 

evidence on the certificate. ‘The following 16 States did 

not report legitimacy on the birth record in 1963: 

Arizona, Arkansas, California, Colorado, Connecticut, 

Georgia, Maho, Maryland, Massachusetts, Montana, 

Nebraska, New Hampshire, New Mexico, New York, 

ONahoma, and Vermont. 

Live- bin% o~der.— Live-birth order is derived 

from entries on the birth certificate and refers to the 

number of children born alive to the mother including 

the sample child. 

CO1OY.—Color is recorded or derived from entries 

on the birth certificate. The category “white” includes 

births to parents classified as white, h4sxican, or 

Puerto Rican. Nonwhite births include births to parents 

classified as Negro, American Indian, Chinese, Japanese, Aleut, Eskimo, Hawaiian, or part-Hawaiian. 

Age of mother.— Age of mother is recorded or derived from entries on the birth certificate. 

B~~th wei.gkt. —In almost all cases weight was recorded on the certificate in po~nds and ounces. It has 

been converted into grams by taking one pound equal 

to 454 grams. 

Completed weeks of gestation.— This item is presented in this report exactly as recorded on the certificate. 

Information From the Questionnaire 

Employment status.— This term covers the categories “not employed” and “employed.” 

Mother~s employment duving &’egnancy.-This is 

defined by the mother’s response that she was employed 

either full time or part time ou:side the home at any 

time during pregnancy. 

Family income. —Family income refers to the 

total of all income received during the preceding year 

by all persons related to each other by blood, marriage, 

or adoption and living in the household when the baby 

was born. fncome from all sources is included, such 

as wages, salaries, unemployment compensation, and 

help from relatives. 

Visit fov medical cave.—A visit is defined by the 

response from a physician or a medical facility that 

the woman had been seen during the 12-month period 

before her child was born. The number of visits was 

obtained by adding all visits reported from all sources 

which furnished care to the woman. 

000


31 
APPENDIX Ill 

SOURCE FORMS 

Certificate .of Live Birth 

Form .Pmovd


B!,d’U Bum,,” No, W-R874 .2.


CERTIE’ZW.TE OF LIVE BIRTH STATE OF BIRTH No. 

PLACE OF mrwn ,2. ~$Tt17ERES:DWtCE OF MOTHER ;~’;hcf~ mrJiAfrhe?] 

d. COUNTY 

k CITY. TOWN. OR LOCATION c, CITY, TOWN, OR LOCATION 

c. NAMEOF (If .c4 in k+@fal, gwe 81?cc1addrtw) d. STREETADDRESS 

HOSPIThLOR 

INSfi ~T1ON 

d, IS WACE OF BIRTH INSIDE CITY LlMK3? ,, 1SR33!oENCE INSIDECITY LlMlT31 /. IS RESIDENCEON A FARM1 

YFSIJ ?wn YESD NOn YES •l NOD 

3. Namr First Middle Lad 

$ ;% “r


c


> 4. SEX 5u. THIS BIRTH W IF TWlfl OR TRIPLET. WASCHILD 30RN 6, DATE Month Dar Yeor


SINGL3 13 TWIN � TRIPLET o 1ST � 2D � 30 � BI:;H 

7. NAME Fi,d Middle .kf 8, COLOROR RACE 

9. AGE (A1 time./ fhh birth) 10, BIRTHPMCE (Slult or {.,+7” COUn!W) 11.. USUALOCCUPATION I lb, KIND OF BUSINESSOR INDUSTRY 

VEARS 

: 12 MAIDEN NAME First Middk Lad 13, COWR OR RACE 

\ 14. AGE (At fimt of this birlh) 15, BIRTHPLACE(Staft w Jwcion Counlrv) 16. PREV1OUSDELIVERIESTo MOTHER (Do NOT include /h& birlh) 

YEARS ., Ifmn w., b, Mao ma”, OTHER &U- ,, now ,“”.” /,!.1 d..lth. *THI?E! *.f&O” :4; w#r b.m d<,, 6“! a“ :J#;t$r”ddey:”;,.v y .,. mow fi,hr ,. INFORMANT 

3. MOTHER’S MAILING ADDRESS 

12,7 s1aMATun3 18b. ATKNDANT AI’ BIRTH 

1 hmhv c+# 

that lAi# Atd M. 0,0 D. 0.0 MIDWIFFD OTHER (Swl/r) 

we. tam slim 

cm lU date 1&. ADDRESS I&f DATE SIGNED 

dated nbe. 

9. DATERECD. BY LOCALREG. 30. REGISTRAR’SSIGNATURE 21, DATEON WHICH GIVEN NAMEADDED 

BY (Regi#rnr) 

FOR	 MEDICAL AND HL4LTH USC ONLY 

(This 8CCfiOXM LIST k Wed md) 

20.	 LENGTHOF PREGNANCY 23b, WEIGHT AT BIRTH 23. LEGITIMATE 

yECWETED L8. 02 YES a NO O 1 

(SPACEFoR ADDITION OF MEDICALAND HEALTH ITEMS BY INDIVIDUAL ST$TZ31 

32 

I 
Mother Questionnaire 

++” ‘% 

J’ j DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE 

; 

%+ / PUBLIC HEALTH SERVICE WASHINGTON %s, D. C. 

@ “.. 

r 

The U. S. RiliMc Health Service is doing a national study to find out how


much and what kinds of medical and dental care women are receiving during


the yesx before the birth of a child. Nothing is known about the extent


of the care received by expectant mothers, even though such care is of the


greatest impcmtsnce for the future health of both mother and baby. A


knowledge of what is actually happening throughout the Nation till go a


long way in helping to improve the health of mothers snd babies.


The information needed for this study will.be baseclon the experience of 

the mothers of4,000 babies out of the hmillionbornauring 1963. These 

mothers were selectea as 6 ramaom sample of all mothers who have a baby, 

ad you axe one of those so selected. We are therefore asking you to answer 

the questions on the following pages of this form, and to return it to us 

in the enclosed envelop= which requires no postage. 

Please notice that in the first part of the form the questions ask about


every aoctor, dentist, hospital, or clinic from which you receives any csxe


auring the entire year before your baby was born. Your answers should not


be just for-c-—connectedw ith pregnancy, but for any and al.lmedical


sma dental care or checkups &uring these E! months.


All information about you and your baby willbe kept completely confidential.


Your answers will be used for health research only antifor no other purpose.


As you might expect, it is particularly important that we receive your


answers ana those of all.the other 4,000 mothers, since each of you really


represents 1,000 mothers.


Your cooperation in this study is deeply appreciate.


Sincerely yours,


@-x/~


O. K. Sagen, Ph. D., Chief


IiationalVital Statistic Division


National Center for Health Statistics


Name of Child 

Date of Birth File Number


M


33 

L 
Physician Questionnaire 

*N ““%+ q DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE : -Ii
 z


%. @ .: PUBLIC HEALTH SERVICE WASHINGTON ZS,D.C.
 @%. -,+”’ u,. 

r


L 

Your assistance is needed in a small but important sample survey conducted 

by the U. S. Fublic Health Service with the approval of your State Health 

Department. The primery purpose of this survey is to estimate how often 

mothers sre exposed to ionizing radiation in the year preceding a birth. 

The survey will also provide usefil data on the extent to which expectant 

m@.hers avail themselves of medical care. The mothers on whom data are 

being collectedwere identified from a remdom sample of about 4,000 births 

out of the k million occurring in the United States during 1963. 

According to our records, the mother nenmi below was seen or treatedby 

you at some time during the year prior to the recent birth of her child. 

We ask your cooperationin answering the questions on the followingpages, 

which relate to the medical care she received during the one-year perioil 

preceding childbirth. The exact dates coveretLby this perioilare shown 

below. Informationis neeaetion each exposure to ionizing radiation this 

woman experiencefiawing this perioa, irrespectiveof its relationship 

to pregnancy. 

Since the survey is basea on only a small sample of mothers, it is particu­


larly important that we obtain full informationon each. A postage-free


envelope is encloses for your convenience in replying. You may be assured


that your report will be hela in strictest confidenceedused only for


statisticalresearch.


Your cooperationin this study is aeeply appreciateiL


Sincerelyyours, # 

L2/y2!+A0. K. sw% d., chief 

National Vital StatisticsDivision 

National Center for Health Statistics


P


h’ame of Mother Maiden Name 

Address Place of Birth of Child 

City-State Date of Birth File Number 

PERIOD COVERED BY THIS SURVEY: FROM TO 

34

Hospital Questionnaire 

@ EDo% 

*% �,. 

:’ * DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE 

~’.>..@ #j @ PUBLIC HEALTH SERVICE WASHINGTON z~, D. C.

U*. 

r 

I_ 

Your assistanceis neededin a smallbut importantsamplesurveyconducted


by the U. S. PubMc HealthSerwi.ce
 with the approvalof your StateHealth


Department.The primarypurposeof this surveyis to estimatehow often


mothersare exposedto ionizingradiationin the year precedinga birth.


The surveywill alsoprotideusefuldata on the extentto whiche~ectant


mothersavailthemselvesof me~cal care. The motherson whom data are
 being collectedwere identMied from a randomsampleof about4,OQO births


out of the 4 millionoccurringin the UixLtea
Statesdining1963. 

Accordingto our records,the mothernmmilbelowwas seenor treateaat


your institutionat sometime duringthe year priorto the recentbirth of


her chila. We ask your cooperationin answeringthe qwstiona on the


followingpages,whichrelateto the medicalcare she receivd duringthe


one-yearperioaprecedingchildbirth.The exactbtes covere$by this


perio$are shownbelow. hformationis neede$on eachexposureto ionizing


radiationthiswomanexperiencedam thisperioa,irrespectiveof its


relationship
to pregnancy.


Sincethe surveyis base$on onlya smallsampleof mothers,it is particu­


larlyWportant thatwe obtainfullinformationon each. A postage-free


envelopeM enclosetifor your conveniencein replying. You may be assurea


thatyour reportwillbe held in strictestconfidencead used onlyfor


statistical
reseexch.


Your cooperationin this studyis deeplyappreciated.


Sincerelyyours,


0. K:w~&


XationalVitalStatisticsDivision


NationalCenterfor HealthStatistics


I


Name of Mother Jlaiden Name 

Address Place of Birth of Child 

City-State Date of Birth File Nmnber 

PERIOO COVEREO BY THIS SURVEY: FROU TO 

1 

000 

35
 *V. S. GOVERNMENT PRINTING OFFICE NW8-34~042/19 
OUTLINE OF REPORT SERIES FOR VITAL AND HEALTH Statistics 

Public Health Service Publication No.1OOO 

Sevies 1.	Proqams and collection pYocedures.— Reports which describe the general programs of the National 

Center for Health Statistics and its offices and divisions, data collection methods used, definitions, 

and other material necessary for understanding the data. 

Series 2.	 Data evaluation and methods reseaych. —Studies of new statistical methodology including: experimental tests of new survey methods, studies of vital statistics collection methods, new analytical 

techniques, objective evaluations of reliability of collected data, contributions to statistical theory. 

Series 3.	 Analytical studies. —Reports presenting analytical or interpretive studies based on vital and health 

statistics, carrying the analysis further than the expository types of reports in the other series. 

SeTies 4. Documents and committee repoyts. — Final reports of major committees concerned with vital and 

health statistics, and documents such as recommended model vital registration lavvs and revised birth 

and death certificates. 

SeYies 10.	 Data j%om t?ze Health InteYview SuYvey, —Statistics on illness, accidental injuries, disability, use of 

hospital, medical, dental, and other services, and other health-related topics, based on data collected 

in a continuing national household interview survey. 

SeTies 11.	 Data jYom the Healtk Examination SuYvey.— Data from direct examination, testing, and measurement of national samples of the population provide the basis for two types of reports: (1) estimates 

of the medically defined prevalence of specific diseases in the United States and the distributions of 

the population with respect to physical, physiological, and psychological characteristics; and (2) 

analysis of relationships among the various measurements without reference to an e@icit finite 

universe of persons. 

SeTies 12.	 Data j70m the InstMutionul Population SuYveys.— Statistics relating to the health characteristics of 

persons in institutions, and on medical, nursing, and personal care received, based on national 

samples of establishments providing these services and samples of the residents or patients. 

SeYies 13.	 Data from the Hospital DischaYge SuYvey.— Statistics relating to discharged patients in short-stay 

hospitals, based on a sample of patient records in a national sample of hospitals. 

Series 20.	 Data on mortality.— Various statistics on mortality other than as included in annual or monthly 

reports— special analyses by cause of death, age, and other demographic variables, also geographic 

and time series analyses. 

Sen”es 21.	 Data on nutality, rnawiage, anddivoyce. —Various statistics on natality, marriage, and divorce other 

than as included in annual or monthly reports— special analyses by demographic variables, also 

geographic and time series analyses, studies of fertility. 

SeTies 22. Data porn the National Abtality and Mortality SuYveys. —Statistics on characteristics of births and 

deaths not available from the vital records, basedon sample surveys stemming from these records, 

including such topics as mortality by socioeconomic class, medical es~erience in the last year of 

life, characteristics of pregnancy, etc. 

For a list of titles of reports published in these series, write to: c)ffice of Information 

National Center for Health Statistics 

U.S. Public Health Service 

\\~ashington, D.C. 20201