I

NATIONAL CENTER Series 4

For HEALTH STATISTICS Number 3

VITAL and HEALTH STATISTICS

DOCUMENTS AND COMMITTEE REPORTS

Report of the

International Conference

on the Perinatal and Infant

Mortality Problemof the

United States

Suinrnary of the presentations and discussions at the International Conference on the Perinatal and Infant Mortality Problem of the United

States, Washington, D. C., May 13 and 14, 1965, under the sponsorship

of the National Center for Health Statistics, Public Health Service, U.S.

Department of Health, Education, and Welfare.

Washington, D,C. June 1966

U.S. DEPARTMENT OF

HEALTH, EDUCATION, AND WELFARE Public Health Service

John W. Gardner Wil Iiam H. Stewart

Secretary Surgeon General
Public Health Service Publication No. I()(ltl.series .LNO. :3
NATIONAL CENTER FOR HEALTH STATISTICS

FORREST E. LINDER, PH. D., &%C~07

THEODORE D.WOOLSEY, lkjwy Director

OSWALD K. SAGEN, PH. D., ~$f;@z?z~ ~&C~O?’

WALT R. SIMMONS, hLA., Statistical Advi-ror

3EICE M. WATERHOUSE, M. D., Medical Advi.ror

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

LOUIS R. STOLCIS, hf. A., Executive Ojicer

OFFICE OF HEALTH STATISTICS ANALYSIS

IWAO AM.MORIYAMA, PH. D., Chief

DIVIS1ON OF VITAL STATISTICS

ROBERT D. GROVE, PH. D., Chief

DIVISION OF HEALTH INTERVIEW STATISTICS

PHILIP S. LAWRENCE, Sc. D., Chief

DIVISION OF HEALTH RECORDS STATISTICS

MONROE G. SIRKEN, PH. D., Chief

DIVISION OF HEALTH EXAMINATION STATISTICS

ARTHUR J. MCDOWELL, Chief

DIVISION OF DATA PROCESSING

SIDNEY BINDER, Chiej

Public Health Service Publication No. 1000-Series 4-No. 3

Library of Congress Catalog Card Number 66-60073
CONFERENCE PARTICIPANTS

Julie E. Backer, Ph.D.

Consultant, Research Department

Central Bureau of Statistics of Norway

Oslo, Norway

Katherine Bain, M.D.

Assistant Chief for International Cooperation

Children’s Bureau

Welfare Administration

U.S. Department of Health, Education, and

Welfare

Washington, D.C.

James F. Donnelly, M.D.

Director, Personal Health Division

North Carolina State Board of Health

Raleigh, North Carolina

Charlotte A, Douglas, O.B.E., M.D., D.P.H.

Edinburgh, Scotland

Charles Gershenson, Ph.D.

Associate Director, Division of Research

Children’s Bureau

Welfare Administration

U.S. Department of Health, Education, and

Welfare

Washington, D.C.

Bernard G, Greenberg, Ph.D.

Professor and Head, Department of Biostatistics

School of Public Health

University of North Carolina

Chapel Hill, North Carolina

J, H. de Haas, M.D.

Department of Swial Hygiene

Netherlands Institute for Preventive

Medicine

Leiden, The Netherlands

J. H. de Haas-Posthuma, M.D.

Department of Social Hygiene

Netherlands Institute for Preventive

Medicine

Leiden, The Netherlands

Katherine M. Hirst,

Reading, England

O.B.E., M.B., D.P.H.

Arthur J. Lesser, M.D., M.P.H.

Deputy Chief, Children’s Bureau

Welfare Administration

U.S. Department of Health, Education,

and Welfare

Washington, D.C.

Forrest E. Linder, Ph.D.

Director, National Center for Health Statistics

Public Health Service

U.S. Department of Health, Education,

and Welfare

Washington, D.C.

I. M. Moriyama, Ph.D.

Chief, Office of Health Statistics

Analysis

National Center for Health Statistics

Public Health Service

U.S. Department of Health, Education,

and Welfare

Washington, D.C.

Edith L. Potter, M.D., Ph.D.

Pathologist, Chicago Lying-In Hospital

Chicago, Illinois

Richard A. Prindle, M.D., M.P.H.

Chief, Division of Public Health Methods

Public Health Service

U.S. Department of Health, Education,

and Welfare

Washington, D.C.

Franz W. Rosa, M.D., M.P.H.

Acting Director, Congenital Malformations

Program

National Institute of Child Health and

Human Development

Public Health Service

U.S. Department of Health, Education, and

Welfare

Bethesda, Maryland

III
Edward R. Schlesinger, M. D., M.P.H.

Assistant Commissioner of Special

Health Services

New York State Department of Health

Albany, New York

William J. Schull, Ph.D.

Department of Human Genetics

University of Michigan Medical

School

Ann Arbor, Michigan

Sam Shapiro, B.S.

Director, Division of Research

and Statistics

Health Insurance Plan of Greater

New York

New York, New York

William A. Silverman, M.D.

Associate Pediatrician, Babies

Hospital

Columbia-Presbyterian Medical

Center

New York, New York

William H. Stewart, M.D.

Assistant to Special Assistant

(Health and Medical Affairs)

Office of the Secretary

U.S. Department of Health, Education,

and Welfare

Washington, D.C.

Dyre Trolle, M.D.

The University Department of Obstetrics

and Gynecology

Rigshospitalet

Copenhagen, Denmark

Myron E. Wegman, M. D., M.P.H.

Dean, School of Public Health

University of Michigan

Ann Arbor, Michigan

Jacob Yerushalmy, Ph.D.

Director, Cooperative Study of

Child Development

University of California

Oakland, California

NATION’iL CENTER FOR HEALTH STATISTICS—,CONFERENCE STAFF

Helen C. Chase, Dr.P.H.

Statistician, Office of

Health Statistics Analysis

Barbara J. van den Berg, M.D.

Visiting Scientist

Office of Health Statistics

Analysis

Elizabeth W. Curran, A.B.

Statistician, Office of

Health Statistics ,inalysis

Iv
-—. .——. .— .

CONTENTS

Introduction ----------------------------------------------------------

Greetings— Dr. Forrest E. Linder ---------------------------------------

Opening Remarks—Dr. Iwao M. Moriyama, Chairman ---------------------

Major Findings of the Forei~Stqdies -----------------------------------

Scotland—Dr. Charlotte A. Douglas -----------------------------------

England and Wales —Dr. Katherine M. Hirst ---------------------------

Norway— Dr. Julie E. Backer ----------------------------------------

Denmark—Professor Dyre Trolle ------------------------------------

Netherlands—Dr. J. H. de Haas -------------------------------------

Infant Mortality Problems in the United States—Mr. Sam Shapiro ---------

Discussion ---------------------------------------------------------

Differential Factors in Infant Mortality ---------------------------------

Statistical Artifacts-Dr. Bernard G. Greenberg ----------------------

Table 1.

2,

3,

Change in period of gestation for which fetal death registration

is required: 10 States of the United States, 1950-63------------

Change in ratio of fetal deaths by week ofgestation to all fetal

deaths 20 weeks and over, and the relative changein reporting,

when minimum period of gestation required for registration

was lowered: 10 States of the United States, 1950-63-----------

Percent of live births of 2,500 grams or less: Minnesota and

North Dakota, 1955-59----------=--------------------------

Discussion ----------------------------------------------------------

Socioeconomic Factors–Dr. Barbara J. vanden Bergand Dr. Arthur J.

Lesser -----------------------------------------------------------

Medical Factors—Dr. William A. Silverman ---------------------------

Table +$. Index of fetal maturity ---------------------------------------

Suggestions for Further Smdy ------------------------------------------

Definitions and Registration Practices---- ----------------------------

Determinantsof InfantMortaliW --------------------------------------

Medical Factors Related to Infant Mortality ----------------------------

Summary -------------------------------------------------------------

Page

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VI

IN THIS REPOR T a summavy of the international conference on the

perinatal and infant morbidity and mortality problem in the United

States is presented. The conference was held in Washington, D. C., on

May “13 and 14, 1965 under the sponsorship of the National CenteY for

Health Statistics. The major findings of studies presented at the conference by investigators from DenmaYk, Englana!and Wales, the Netherlands, Norway, Scotland, and the United States are summarized here.

T~ends over the past 30 years as well as the cw?’ent situation in perinatal and infant movtality are described. Statistical social, demographic,

and medical artifacts associated with infant mortality are discussed in

an effozt to deteymine the reasons fov the mortality differences between

the United States and the WesteYn Euvopean countries. Suggestions ave

made foy futuye study of vayious aspects of the infant mortality pvoblem.

The infant mortality rates have decreased impressively during the past

30 yeavs; however, in the 1950’s the rates of decline for fow of the

countyies, including the United States, slowed down. The vate of decline

in the United States decyeased the most, and the deceleration started

earliev than it did in most of the other countries. The infant” mortality

vates in Denmavk and the Netherlands are still declining with no apparent

intem-uption.

Lavge Deductions in infant deaths have been attributed to declines in infectious disease moytality. There have been limited reductions in deaths

from diseases of eavly infancy and congenital malformations, and an increasing incidence of perinatal deaths attributed to disoyders of uncertain etiology. All investigators descyibed incveasinguse of hospitals fov

deliveyy. There has been an increasing incidence of low-birth-weight

infants in the United States. In countvies wheve some measure of socioeconomic level is available infant mortality is highev in the lower classes,

and the mortality differential between the upper and lowev classes is

increasing.

Comparison of statistical, demographic, and medical parameters of infant mo~tality showed no clear-cut explanation of the significant international differences. Further research of infant and perinatal mortality

pvoblems was wged.

SYMBOLS

Data not available------------------------ ---

I

Category not applicable------------------- . . .

I

Quantityzero ---------------------------- -

I

Quantitymore than O but less than0.05---- 0.0 I

Figure does not’meet standards of

reliability or precision ------------------

*

L
REPORT OF THE

INTERNATIONAL CONFERENCE ON THE

PERINATAL AND INFANT MORTALITY PROBLEM

OF THE UNITED STATES

Elizabeth W. Curran, O~Ce of Health Statistics Analysis

INTRODUCTION

Two features were noted about the infant

mortality rate in the United States in the

IQ50’S: (1) the virtual halt in the rate of decline

of infant mortality after a Iong period of rapid

decline,1 and (2) the unfavorable position of

United States’ infant mortality compared with

that of many other countries. 2 These two points

were viewed with concern because health authorities had for many years pointed with pride to the

high rate of decrease in infant mortality in the

United States. In an attempt to illuminate the

problem areas related to infant mortality in the

United States, a comprehensive study of perinatal

and infant mortality in several Western European

countries of similar social and economic development was arranged. These countries were Denmark, England and Wales, the Netherlands.

Norway, and Scotland. They were selected because

of the low infant mortality rates in these countries

over a long period of time, and because of the

weH-developed vital statistics systems with relativel y stable definitions and reporting requirements.

The National Center for Health Statistics

sponsored, on May 13 and 14, 1965, a conference

on the perinatal and infant mortality problem of

lhforiynmrt, I. hi.: Recent change in infant mortality trend.

Pub. Hca2th Rep. 75:391-405, hiay 1960.

~Shupiro, S,, and Moriyarna, I. M.: International trends in

infwt mortulity and their implications for the United States.

Am. J. Pub. Health. 53:747-’760, May 1963.

the United States. The participants included the

foreign investigators and various workers in the

United States concerned with the problem of infant

mortality, The purpose of the conference was to

determine the reasons for the position of the infant

mortality rate in the United States.

Following is a summary of the conference

proceedings.

GREETINGS

DY. Fon’est E Li~eY

In one respect this meeting is a rather

unique event for the National Center for Health

Statistics. The Center and its component parts

have had a long history of meetings on a national

basis with some international participation for

considering questions of mortality classification

and other technical questions related to the whole

range of health statistics. However, this is the

first time that we have called together an international group that is focusing its work on the

meaning of United States figures, and on whether

the apparent substantive indications of the numbers have validity in terms of interpretations that

might be given to them. I think this is a forward

step in our program in the National Center

for Health Statistics and I hope it is a precursor

of other fruitful conferences of this kind in the

future.

We will look upon this conference as establishing a pattern which we hQpe to repeat, and

which we hope will be effective in bringing about

closer collaboration between the statisticians in

1
this country and those in countries that have

similar types of problems in vital and health

statistics.

It is ~ot on the agenda of this meeting to

discuss what might be done in a public health

program about finclings shown by the figures

or the causative situations that are indicated by

our discussions here,. The problem is to explore

the validity and the meaning of the infant mortality

rate in the United States to see whether the

comparisons of that figure with other countries

are technically valid, and to what extent the

discrepancies and the differences are attributable

to either technical questions or to social, demographic, or economic features. It will then be the

responsibility of program directors in the various

public health and medical agencies to develop

required and appropriate action programs.

OPENING REMARKS

Dr. Iwao M. MoYiyama,

Chairman

LTpto about 15 years ago, the infant mortality

rate in the United States was among the lowest

in the world. In the period 1935 to 1950, the infant

mortality rate declined at an accelerated pace in

the United States and in other countries of low

mortality, but in the 1950 decade, the rate of

decline of infant mortality in the United States

began to slow down. Incidentally, the change in

mortality conditions was not peculiar to the period

of infancy. The rate at other ages also leveled

off in the United States, but these changes came

several years after the beginning of the deceleration in the infant mortality rate.

The rapid decline in the infant mortality rate

in the late 1930’s and the 1940’s appears to be due

mainly to a reduction in deaths from the infective

diseases. This was also generally true for the

older ages. Although further reductions in the

death rates for the infective diseases are still

possible, the gains to be made through infectious

disease control are limited. However, the infant

mortality rate for the United

about 20 percent lower today

pneumonia had been eliminated.

2

States would be

if deaths from

One of the intriguing questions is why the

rate of decline of infant mortality rates for

countries such as the United States, England

and Wales, and Norway has been checked, whereas

the rates for Denmark and the Netherlands have

continued to decline without apparent interruption.

This situation would not be tcm surprising if

the level of the rate for Denmark and the

Netherlands were considerably higher than that

for the other countries; however, the contrary is

true. Indeed, the recorded infant mortality rate

for the Netherlands is now among the lowest in

the world. If the present movement of the deazh

rates were to continue, there would be no question

in the future as to the country with the lowest

perinatal and infant mortality rates.

Obviously, the decline in mortality rates

cannot continue indefinitely; at some point the

irreducible minimum must be reached. The

irreducible minimum is anybody’s guess, but it is

significant to us that the recorded infant mortality

rate for the Netherlands at this point in time is

about 15 per 1,000 live births, whereas the rate for

the United States is about 25. The position of the

United States has worsened in relation to that of

other countries. What is more, the gap is widening.

I find this to be a distressing situation only

if it means that this country is suffering unnecessary infant loss, and one of our main tasks

here is to determine whether international differentials in mortality are real or apparent. We

need to take a critical look at the situation and

rule out, as far as possible, the effects of

artifacts on the comparisons. If the observed

differences are real, we would like to identify the

reason for the differences, and if we are unable

to determine the reasons for the differences-and

this is likely in many cases—I hope that we can

suggest studies that will provide the answers.

It seems to me that there are two promising

leads that should be examined concerning the

problem of the relatively high infant mortality rate

in the United States. One relates to the difference

between the rates for the United States and those

of other countries. The other relates to the

marked decrease in the rate of decline for the

ififant mortality rate in the United States. Either

or both of these factors might provide the reasons

for the present unfavorable international pxition

of the United States with respect to the infant

mortality rate.
MAJOR FINDINGS

OF THE FOREIGN STUDIES

Scotland

DY. Charlotte A. Douglas

In Scotland there had been impressive declines in maternal, fetal, and infant mortality

from 1935 until the early 1950’s when the decline in

the mortality rates became more gradual. Since

then there have been only slight improvements.

Dr. Douglas attributed the decline to the comparatively low birth rate plus the increased availability and utilization of maternity hospitals and

maternal and child care. Today, 80 percent of

the live births, 90 percent of the fetal deaths, and

90 percent of the premature births are delivered

in maternity institutions. The average stay in the

hospital is 9 days.

Fetal death registration was instituted in

1939, and since then the fetal death rate has decreased 55 percent. Improvement has been greatest for deaths due to difficult labor, ill-defined

conditions, and toxemias.

In general, neonatal mortality is the result

of intra-uterine conditions and birth hazards.

‘Ihese causes are responsible for 98 percent of

first-day deaths, 95 percent of first-week deaths,

and 90 percent of first-month deaths. Postneonatal

mortality, however, is chiefly caused by respiratory diseases and congenital abnormalities.

Illegitimacy in Scotland is more a social

problem than a medical one. Now, the illegitimacy

ratio is 5.2 percent of live births. Although these

children are a social problem which may persist

in following generations, the effect on the overall

infant mortality rate is comparatively low.

Dr. Douglas placed great emphasis on therelationship between social class and fetal and

infant mortality. For statistical purposes, the

social class of the infant is determined by the

father’s occupation. There are five. defined

classes, ranging from professional and managerial occupations (class I) to unskilled workers

(class V). Although the infant morta.&.y rates in

all five classes have declined over the past 30

years, the distinction between classes I and Vhas

widened. In 1939, the fetal death rate of class V

was 11/4 times as high as that of class I; in 1963,

it was about 21/3 times as high as that of class I.

Neonatal mortality shows a similar trend in class

distinction. In 1939, class I had a neonatal

mortality rate of 25.9 and class V of 39.9,

whereas in 1963, class I had a neonatal mortality

rate of 9.5 and class V of 22.3. The gap between

these two social classes” is greatest in the postneonatal period; and instead of closing, this gap

has widened throughout the years, for in 1939,

the deaths in class V were 6 times that of class

1, whereas in 1963 they were 13 times as great.

The Scottish Registrar General’s Report for

1943 included an appendix analyzing infant mortality and fetal deaths by social class for the year

1939, Another tabulation was published in the

report for 1944, and these statistics have been

published every year since then. In 1943 Professor

Richard Titmuss drew attention to the inequalities

in infant mortality rates in the different social

classes. His findings were confirmed by Morris

and Heady in 1956. In France, similar mortality

differentials were found by CroZe, and in Hungary

by Gzabady.

For some time in Aberdeen, Baird, Kincaid,

and others have been working on the problem of

reproductive efficiency and have established the

fact that there is an association between maternal

stature and pregnancy outcome. The measure of

maternal stature was used as an index of the

“biological fitness” of the mother. They have

shown that for each social class, as a general

rule, the taller the woman the less likely is she

to produce a fetal death or an early neonatal

death.

This tendency to show a widening difference

between the social classes is difficult to understand in a country where medical care is available

to all and where there is ample maternity hospital

accommodation for any woman requiring expert

care. It is true that the more intelligent women

tend to seek prenatal care earlier in pregnancy

than do women who may be careless about their

health, and who are also overburdened with

heavy household duties and the care of other

children. This situation, might be expected

to explain to some extent the differing

mortalities between the classes, since antenatal

care, however good, cannot be the whole explanation. It is true that family size with the concomitant

extra burdens on the mother can be exhausting.

3
Should the pregnancies be too rapid, depletion of

the mother’s reserves of iron may lead to

biological and physical exhaustion. However, only

about 11 percent of the women in this country now

have more than four children, and” the average

family size is only 2.5 children. So, some further

explanation must be sought.

It would appear that the woman’s growth

is influenced not only by heredity but also by

nutrition, housing, economic conditions, and the

way of life of her parents. It has been found

that there is a relationship between the number

of siblings in the mother’s parental house and

her future reproductive capacity. In nonmanual

workers there is an increase in perinatal mortality

only when the mother was one of five or more

children; while in the unskilled classes there is an

increase when the mother had only one sibling.

These facts appear to lead to the generalization that the smaller the family the better will be

the education and upbringing of the future mother.

There is also a continual process of social selection and the usual tendency is for the average

woman to rise out of her social class or remain

within it. In this way, as the women with better

reproductive potentialities move upwards, those

remaining in classes IV and V are biologically

and physically less able to produce and rear

children successfully. Probably as these lower

classes lose more and more women who are

reproductive y efficient, the perinatal and infant

mortality rates will remain above the average.

England and Wales

Dr. Katherine M Hirst

In England and Wales the total infant mortality

has declined through the years, but it began to

level off during the 1950’s as did that of the

United States. Perinatal mortality began to level

off at the end of the 1940’s; but in the midfifties

fetal mortality began to fall again, while firstday mortality remained stationary. Postneonatal

mortality appeared to start rising in the midfifties.

Three main causes of death were discussed—

infections, diseases of early infancy, and congenital malformations. Infant mortality from infections has decreased steadily since 1935. While,

in general, deaths from infective conditions

continued ta lessen during the 1950’s, deaths

from pneumonia and bronchitis and from gastroenteritis stopped declining and began to level off

around 1957.

Diseases of early infancy, which include

immaturity, birth injuries, and asphyxia and

atelectasis, are responsible for 75 percent of

first-day mortality. In this cause group, immaturity appears to be a strong factor in neonatal

deaths, as half of the deaths ascribed to birth

injuries and two-thirds of those ascribed to

asphyxia are associated with immaturity. There

has been no decline in first-day deaths (mainly

caused by diseases of early infancy) since 1950.

There has been virtually no change in the

mortality rate for congenital malformations during the fifties.

Low-birth-weight babies constitute one of the

important high-risk components of infant mortality. In England and Wales the proportion of

babies weighing 2,500 grams or less at birth is

about 6.6 percent of all live births. This percentage

has remained unaltered for the past 10 years. Also,

the proportim of babies weighing 1,500 grams or

less at birth has remained at 11 percent of the

total of low-birth-weight babies for the past 10

years. Neonatal mortality of low-birth-weight

babies has decreased from 155 neonatal deaths

per 1,000 live births of 2,500 grams or less

in 1953 to 128 in 1963; however, mortality of

infants under 24 hours old has remained almost

at a standstill.

There are geographical factors in infant ,and

perinatal mortality in England and Wales, in that

there is a southeast to northwest gradient with

the lower fetal and infant mortality rates in the

southeast. However, the gap is gradually closing.

The urban and rural areas both show this southeast to northwest gradient.

As in Scotland, there is a fairly steep gradient

from socioeconomic class I to socioeconomic

class V which does not seem to be narrowing.

Despite the fact that the gap between the incomes

within these classes has been decreasing, the

differences in the infant mortality rates between

classes I and V have increased slightly. Dr. Hirst

pointed out that one reason for the widening

disparity is that cultural customs of a group do

not necessarily change as rapidly as do economic

situations. One of the most important steps

in lowering infant mortality is the acceptance of

new ideas, such as receiving antenatal care early

in pregnancy or being hospitalized for birth;

4
however, changes in attitudes and ways of life

take time.

Migration between classes may tend to keep

the disparity evident, For example, families with

poor health may drift into the lower socioeconomic

classes. On the other hand, in connection with the

maternal stature and infant mortality correlations

discussed by Dr. Douglas, the woman who marries

into a higher social class will, on the average, be

taller, will have a better standard of education,

and, if she is working, will have a better occupational status than the woman who marries into a

lower social class. These attributes carry a lower

perinatal mortality.

In conclusion, Dr. Hirst pointed out that the

future outcome of pregnancy will depend on two

views—the long-term view, which is the generation effect of a mother’s background, and the

short-term view, which uses parameters of

pregnancy to define the immediate risk to the

mother. It is important to realize that the

immediate risk is evident because of the mother’s

background. At any one point in time the mother’s

background cannot be changed, but action can be

taken to minimize the immediate risks involved

in parturition. For England and Wales this means

selection for hospital confinement. At present, 65

percent of the pregnant women are hospitalized for

birth. This is the national average, with wide local

variations. On the basis of high risk groups —wom -

en over the age of 35, those with four or more

children, those who require admission on social

grounds, all primigravidae, and all women with

medical or obstetric abnormalities—hospital ac -

commodation should be provided for at least 70

percent of the pregnant women in all areas

throughout the country.

Norway

Dr. Julie E. Backev

The infant mortality rate for Norway has

declined from 91.1 infant deaths per 1,000 live

births in 1901 to 16.9 in 1963. The rate of

reduction has varied considerably from period to

period, For instance, the downward trend was

relatively

to an end

rapid in the thirties, but came almost

during the Second World War. During

the first decade after the war the relative declim

of the infant mortality was the greatest experienced in Norway during this century. But in the

middle of the 1950’s this rapid downward trend

was again leveling out, and lately the annual reduction ratio has been about the same as in the

years just before the Second World War.

Perinatal mortality has declined 39.5 percent

in the last 30 years; mortality of infants 7 to

27 days old was 70 percent lower in 1961-62

than during 1931-35; and deaths of infants 1 to 11

months were 75 percent lower. While in 1900,

38 percent of all perinatal and infant deaths occurred before delivery, during delivery, or before the end of the first week of life, in 1961-62,

75 percent of the perinatal and infant deaths occurred before the end of the first week of life.

In 1962, 80 percent of the perinatal deaths

occurred before or within 24 hours after birth,

This relationship has remained unchanged during

this century. However, with the better obstetrical

services more infants, especially premature and

not viable, which in years past would have died

prior to or during birth, now have been born alive

and die during the first day of life.

Tuberculosis, the common infectious diseases, diarrhea, and enteritis have been practically eliminated as causes of infant deaths. Also,

mortality from pneumonia and other diseases of

the respiratory organs has been considerably

reduced.

As infections caused by external factors have

become better controlled, deaths from congenital

malformations and diseases of early infancy have

become increasingly prominent. While only 27

percent of all infant deaths in 1900 were caused

by this group, 76 percent of the infant deaths in

1962 were caused by it.

As with England and Wales, immaturity has

been the most frequently reported of the causes

of early infant deaths. Not only has immaturity

been linked with approximately one-third of all

deaths assigned to congenital malformations and

diseases of early infancy since 1930, but it has

also frequently been mentioned as a subsidiary

cause of death for other diagnoses. In the last 10

years, immaturity has been reported by physicians

either as a pyimary or as a secondary cause of

death for 64 percent of all infant deaths in the

first month of life which were classified to dis -

5
eases of early infancy. Of’ the deaths which

occurred after the first month of life 34 percent

have been attributed to or Iinked with immaturity.

Dr. Backer indicated that, as in other countries, the illegitimate child in “the,.first year of

life has always had a greater risk” of death, but

the proportion of illegitimate babies in Norway

has not been sufficiently high to affect the

national level of infant mortality.

There. is a direct relationship ~etween the

mother’s age and the mortality of a baby before

or during delivery. In a study of “this relationship among legitimate births, it was found that the

risk of a fetal death increases with the age of the

mother. Among mothers aged 40-45 years the

fetal death rate was 28 per 1,000 live births and

fetal deaths—almut three times the rate for

mothers in their early twenties. In all age groups

of mothers, the fetal death rate was considerably

higher for first-born infants; however, during the

last 20 years, the fetal death rate for first-born

infants has decreased relatively more than that for

children born later.

Dr. Backer attributed the great declines in

Norway’s infant mortality to general improvement

in environmental factors, which cause infections,

and in socioeconomic conditions. The increasing

income of the families and the decreasing number

of children per family implied better nutrition,

housing, environmental and personal hygiene, in

short, a more healthful standard of living. The

economic progress also provided a basis for the

introduction of a comprehensive system of social

security and advances in public health and medical

services with special bearing on the welfare of

the’ mother and child. One indication has been

the increasing number of births occurring in

hospitals and maternity homes—from 75 percent

in 1951 to 96 percent in 1963. As a rule, the

“.midwife delivers the child without medical assistance, but in hospitals and clinics a doctor

is always available. Therefore, in”all cases where

complications of labor may be expected, the

mother is sent to a hospital.

Among the different legal measures which

have contributed largely to the reduction of the

maternal and infant mortality and morbidity in

Norway are the introduction of national sickness

insurance in 1911,in 1936the provision for leave

of absence from work of pregnant women before

and after delivery., and in 1946 special ,a~low~”ce

for all breadwinners supporting more than one

child.

Denmark

Professor Dyve Trolle

Denmark’s infant and perinatal mortality

rates have decreased by varying degrees. During

the period 1921 to 1962, the fetal death rate

decreased 52 percent to 11.9 per 1,000 live

births and fetal deaths; the perinatal mortality

decreased 44 percent to 24.9; and the total infant

mortality under 1 year of age declined 74 percent

to 20.0 per 1,000 live births. While late neonatal

mortality of 7 days-1 month decreased 80 percent

and postneonatal mortality declined 90 percent,

early neonatal mortality under 7 days declined

only 35 percent.

The relative declines by age have changed as

follows :

I

Percent

Under 1 year -- 39 ;; 31

Under 1 month1-11 months--- H 60 ;;

The smaller decline for deaths of infants under

1 month old is due to the fact that neonatal deaths

are dominated by causes of death which have been

subjected to limited reductions such as congenital

malformations, birth injuries, and immaturity.

The large decreases in mortality have been most

conspicuous for infective and parasitic diseases

and for diseases of the respiratory and digestive

systems. There has been an excess mortality

from. most causes of death and in all age groups

at death for males.

The number of infants born out of wedlock

decreased from 1930 to the end of the 1950’s;

however, the number has increased since then.

In 1962, 8 percent of the live-born infants were

illegitimate. Illegitimate births are considered

6
among the high risk groups, and the excess mortality for illegitimate births in Denmark is seen

for all causes except congenital malformations

and hemolytic diseases.

Infant mortality in relation to parity and the

mother’s marital status shows increasing mortality with higher parity for infants of 2,500 grams

or less of both unmarried and married mothers.

For infants weighing over 2,500 grams at birth,

mortality is lowest for second parity. In all

cases mortality is higher for infants of unmarried

mothers.

Since 1945, all women have been allowed nine

free consultations during pregnancy. Three of

these are with a physician at the following

recommended intervals: (1) as early as possible,

(2) in the 25th week, and (3) in the 34th to the 36th

week of pregnancy. The other six are to be with

a midwife in the 20th, 30th, 33d, 37th, 38th, and

the 39th weeks. The proportion of live-born infants

whose mothers take advantage of these free visits

has been increasing over the last 16 years.

Delivery of infants in hospitals has been

increasing in Denmark. In 1962, 46 percent of the

births were delivered at home and three-quarters

of these were attended by a physician. Otherwise,

10 percent of the deliveries were at private clinics,

21 percent were at general hospitals, and 23

percent were at obstetric departments.

Since 1937, when a health service law for

prevention of disease and death during the first

year of life was enacted, specially trained nurses,

the so-called public health nurses, have been

employed to supervise infants under 1 year in

private homes. In 1962, there were 658 public

health nurses employed, a ratio of approximately

118 live births per nurse. Although their number

is increasing, there are still many rural districts

with no public health nurses.

Immediately after delivery, the midwife or

doctor notifies the public health nurse and shortly

thereafter she pays her first visit to the home

in question. In 1962, two-thirds of all infants

were supervised in this way. Euring the infant’s

first year of life, the nurse pays 12 visits, most

of them during the first month. At these visits,

the nurse advises the mother on nursing and

feeding, recommends free prophylactic medical

examinations, and advises visits to a physician

at symptoms of any diseases. Since 1963 she has

also routinely made examination for phenylketonuria. In addition, under an act of April

1946, each child less than 7 years old may be

examined nine times free of charge by a physician,

three of which are during the first year of life

at the ages of 5 weeks, 5 months, and 10 months.

Netherlands

Dr. J. H. de Ham

For three reasons the Netherlands stands

in a special position with respect to infant loss:

(1) the rates are low compared with other

countries, (2) hospitalization at birth is extremely

low, and (3) infant care has a relatively long

tradition. The medical demography of the Netherlands is characterized by a relatively high birth

rate, low mortality rates, and a disappearance of

common infectious diseases of childhood and

tuberculosis.

In contrast to the experience of the United

States, England and Wales, and Scotland, fetal and

infant mortality rates in the Netherlands have

continued to fall since 1950. Infant mortality

has decreased from a rate of 51 infant deaths per

1,000 live births in 1930 to 29 in 1948, to 20 in

1956, to 15 in 1964.

Before World War H fetal mortality was on

the average 50 percent higher than first-week

mortality, and since 1950 about 30 percent. The

position of early neonatal mortality (deaths of

infants under 7 days in age) has changed relative

to postnatal mortality (deaths of infants 1-51

weeks in age). In the early 1920’s, postnatal

mortality was three times as high as first-week

mortality, and at present, first-week mortality is

twice as high as postnatal mortality.

In the first week of life, birth injuries,

immaturity, and congenital malformations have

been the dominant causes of death, From 1953-

54 to 1961-62 they decreased by 20-25 percent.

Other diseases of early infancy have been fourth in

importance, and have more than halved during

these 8 years. During the same period total

first-week mortality decreased by 25 percent.

In the postnatal period congenital malformations are the main cause of death and the rates

are scarcely decreasing.

defined and other causes”

The subgroup “illoccupies the second

7
place, and pneumonia and other respiratory diseases the third place. The rates for both of

these groups are rapidly decreasing.

As medical certificates do not exist in the

Netherlands, the exact distributions of birth

weights and period of gestation are not available.

However, independent surveys have been conducted in order to determine the extent ~f

prematurity. In 1954 it was estimated that 5?2

percent of the live ‘births were premature. As in

all other countries, prematurity is of paramount

significance in perinatal mortality. During the

filst week of life, the risk of dying is about

20 times higher for premature infants than for

infants born at term.

Infant mortality rates in the Netherlands still

show the classical picture, as in Scotland and

England and Wales, of a wide range by social

class. In 1961-62 first-week and postnatal mor -

tal:.ty of class I (free professions and higher

officials) were 15 percent lower, and those of

class V (nonfarm laborers—skilled and unskilled)

were 10 percent higher than the average of the

whole country.

After World War II, the Netherlands became

one of the Western European so-called welfare

states—social security for the great masses,

little unemployment, moderate wages with increasing standard of living, no real poverty compared with prewar conditions, no serious alcoholism, and at last but not least, an average

nutrition of reasonable quality and quantity. The

Health Insurance Act of 1941 made health insurance compulsory under a certain level of income,

giving the laborers and their families the legal

right to medical care—family doctor, hospital,

medicines, and so forth.

Obstetric care in the Netherlands has had

three characteristics which are interrelated:

(1) domiciliary confinement by general practitioners and midwives is far more usual than

institutional confinement; (2) midwives give prenatal and natal care as independent practitioners;

and (3) a special organization provides maternity

care and help in the household for the family,

By tradition, the place of delivery has been at

home. In the Netherlands only 20 percent of the

live births in 1950 were delivered in a hospital;

and in 1963, 30 percent of the live births occurred

in hospitals. The proportion of fetal deaths

delivered in hospitals amounts to about 60 percent.

Perinatal mortality in home deliveries is very

low—in a decade decreasing from 22 to 12 per

1,000—compared with that in hospital deliveries—

decreasing in the same period from 65 to 53 per

1,000—because pathological cases are concentrated in hospitals. At present, obstetric aid

is entrusted to midwives in 35 percent, to

general practitioners in 45 percent, and to

obstetricians in 20 percent of all births.

To offset low hospitalization, an organization

has been founded to provide care to the mother

and the newborn infant during childbirth and to

temporarily manage the household duties, In 1950,

this organization covered one-fourth and in 1963

half of all home deliveries, Perinatal mortality

in the group with maternity-home help is half

the national rate.

For the past 60 years, infant welfare centers

have been set up throughout the Netherlands to give

periodic examinations to infants. In 1930, there

was one infant welfare center per 450 live births,

while in 1960 there was one per 100. At present,

the average number of examinations in the first

vear of life is 10 to 11.

In conclusion, Dr. de Haas stated that:

the Netherlands belongs to the privileged

group of small industrialized countries with

low rates of infant loss. This favorable

situation was not reached because of evaluation and planning (at least not before 1950) but

because of a long tradition of basic infant

care in the family supplied by district nurses

and welfare centers and supported by elementary social security and a rising standard

of living.

The expectation is warranted that in 1970,

fetal deaths will be reduced to 10-11 per

1,000, first-week mortality to 8-9 per 1,000,

postnatal mortality to 3-4 per 1,000, perinatal

mortality to 18-20 per 1,000, and infant

mortality to 11-13 per 1,000.

8
INFANT MORTALITY PROBLEMS

THE UNITED STATES

My. San2 Sha@YO

IN

Mr. Shapiro opened with a brief background

of the 1950 demographic and socioeconomic

picture in the United States, Hepointed out that

the leveling off of the infant mortality rate in

the United States came earlier than it did in most

of the other countries with which comparisons

were being made. Furthermore, in more recent

years the leveling off has resulted in higher

neonatal and postneonatal mortality rates in the

United States than inmost of these other countries.

The United States has always had a comparatively low fetal mortality rate; however, the

rate of decline appears to have slowed down more

than for other countries. The perinatal mortality

rate (fetal deaths of 28 weeks’ and over gestation

and deaths of infants under 1 week old) maintained

a comparatively middle position in the postwar

period. Currently it is one of the highest among

the countries under discussion.

Mr. Shapiro next turned to discuss the issue

of risk factors and what has been happening in the

United States in relation to them. The male-female

differential in infant mortality has changed very

little over the past 25 years. At the present time,

there is an excess of 30 percent in the mortality

among male births.

It is apparent that the rate of decline for both

the white and nonwhite populations decreased during the 1950 decade. Although the overall picture

that is found for white and nonwhite persons combined is reflected in the situation for the white,

the decrease in the rate of decline was more

serious in the nonwhite population, During the

1950’s and 19(j0’s the differentials increased so

that in 1962 the rate for nonwhite infants was

about 85 percent higher than that for white infants.

During the 1950 decade, infant mortality

decreased more rapidly in the nonmetropolitan

areas than in the metropolitan areas, and today

there is only about an 11 percent differential

between their rates. It is believed that about 50

years ago urban areas had a higher infant mortality rate than did rural areas. Subsequently,

there was a crossing over with urban areas having

a lower rate. In the early fifties the urban

areas again had infant mortality rates slightly

higher than those of the rural areas. Interestingly

though, this reversal or converging of the urbanrural infant mortality rates in recent years is due

entirely to what has been happening to the white

population; the nonwhite infant mortality rate has

remained lower in urban areas than in rural areas.

The situation in large cities has drawn considerable attention. The infant mortality rate in

many of the large cities has remained unchanged

in the white population, and has increased in the

nonwhite population. Part of the speculation about

this phenomenon is that there has been a migration

among white persons from these large cities into

the surrounding urbanized areas with an important

social class selectivity factor operating. There,

the speculation is that as the higher social class

is moving away from the central city into the

suburban area, a more adverse risk group of the

white population has remained in the cities. In the

nonwhite population the phenomenon has been

different. There has been a migration into the

cities and hence a very substantial increase of

the nonwhite population in many of the cities.

Prior pregnancy history is another risk factor

involved in the outcome of the current pregnancy.

If a mother has a prior fetal loss in her background, there appears to be at least a doubling

in the risk of a fetal death in the current pregnancy. There is also an elevated risk of a premature birth among women who previously have

had a prematurely born infant.

This introduces the factor of birth weight

In the United States in 1950, the first year for

which there are national data, 7.5 percent of the

live births weighed 2,500 grams or less—7.2

percent of white and 10.4 percent of nonwhite

births. The proportion of births at low birth

weights has increased to 8.2 percent (1963)

due almost entirely to a sharp increase in the

rate among the nonwhite population.

There is a fairly clear indication from

data for Upstate New York that the neonatal

mortality rate, from the late 1940’s to the

early 1950’s, decreased among both babies

weighing 2,500 grams or less and those weighing

9
over 2,500 grams at birth; however, there has

been no decrease in the neonatal mortality rate

among the low-birth-weight infants since then.

It is generally. accepted that socioeconomic

class is a very important discriminating factor

in infant mortality. However, there are no data

available for the United States as a whole on this

issue. Dr. Helen C. Chase has reported on the

experience in New York State (excluding New

York City) for 1950-52. One point of interest

relates to the comparatively modest variations in

perinatal mortality (defined as infant deaths under

28 days of age and fetal deaths of 20 weeks’ or

more gestation) by social class based on the

father’s occupation. A one-third gradient in the

loss rate was found between the professional

category and the laborer category (nonagricultural).

There are many difficulties in drawing inferences from cause-of-death information because of the great variation that may exist among

countries in the way cause of death is assigned.

Nevertheless, from the standpoint of international

comparisons it would appear that the United

States cannot single out any one or two particular

causes of death to which to attribute the differentials in either neonatal or postneonatal

mortality. The United States seems to have

an elevated infant mortality in the great majority

of the causes of death.

The final point made was that very recent

events indicate that the infant mortality rate in

the United States is still declining very slowly.

However, no segment of the population is experiencing a large-scale reduction in the rate.

Discussion

The discussion that followed Mr. Shapiro’s

report centered on the problem of social class

differentials. It was pointed out that data from

New York State, exclusive of New York City,

of mortality differentials by social class, as

defined by the father’s occupation, became more

apparent in the postneonatal and early childhood periods. The chance of a low-birth-weight

baby being born dead or of dying within the first

month of life was shown to be the same for all

occupational groups, but the chance of the lowbirth-weight baby surviving later was quite

marked by social class. Professor Trolle remarked that in Denmark, on the other hand,

social class differences were seen both in the

occurrence of low-birth-weight babies and in their

neonatal mortality.

The fact that social class is indeed a difficult factor to analyze was emphasized. Problems

of family disorganization, medical status before

pregnancy, and the nature of prenatal care all

contribute to make this a highly complex situation.

Mr. Shapiro suggested that this view was supported

by data from a study of births in New York City

in 1955. In this study, births were classified

by whether the mother was hospitalized as a

general service ward patient or as a private

patient. The results showed that nonwhite patients

of private physicians had a perinatal loss which

was very similar to the loss among white patients

admitted to the general service ward. This would

seem to indicate that a simple dichotomy between

private care and general service ward care, or,

for that matter, any single measure of social

class will not entirely explain the situation.

DIFFERENTIAL FACTORS IN

INFANT MORTALITY

Statistic I Art if acts

Dr. Bernavd G. Greenberg

Dr. Greenberg led the discussion on statistical artifacts which might possibly affect international comparisons of infant mortality. He

concentrated on three possible artifacts: (1)

definitions and requirements for reporting, (2)

registration and notification practices, and (3)

coding and tabulating practices. Dr. Greenberg

also summarized the significance of various

demographic factors in relationship to international comparisons of infant mortality.

For alI practical purposes, live births and

fetal deaths are defined alike in the United States

and in the Western European countries under discussion. However, requirements for repxting

fetal deaths vary according to the period of ges10
tation for which registration and/or notification

is stipulated by law. The participating foreign

countries require that all fetal deaths after the

28th week of gestation be reported. In the United

States, each State determines its own laws for

registration of vital events. Most of the States

use the minimum gestation period equal to or

greater than 20 weeks; one State, Pennsylvania,

requires that fetal deaths greater than 16 weeks’

gestation be registered, and nine States and New

York City require that fetal deaths of all periods

of gestation be registered.

The variation in registration requirements

may be responsible in part for the variation in the

fetal death ratios. The gestation period at which

reporting is required will affect not only the

total number of fetal deaths, but also the distribution of fetal deaths by gestation periods above the

minimum level required. Dr. Greenberg showed

that in certain States of the United States registration at 20-27 weeks’ gestation was increased

when the minimum period was lowered.

For example, within the past 13 years, 10

States changed their registration requirements

so that the minimum gestation period for which

fetal deaths must be registered was lowered. In

one case, South Dakota, this requirement was

changed back to its former level in 1959. Table

1 shows the year the change was effected and

indicates the change. Analysis of differences in the

distributions of fetal deaths of 20 weeks’ gestation

or more showed that after the registration change

the proportion of reported fetal deaths of 20-27

weeks’ gestation increased in each State. The

overall weighted average ratio for the 20-27

week interval increased from 21.2 to 29.3 (an

arithmetic change of 8.1 as shown in table 2).

In order to determine whether this trend

occurred in other States where no change was

made in the minimal period for which a fetal

death must be reported, Dr. Greenberg looked at

the trend for Upstate New York. Here the requirements for. registration remained at 20 weeks or

more. Data for the years 1950-56 were compared

Table 1. Change in period of gestation for which fetal death registration is required: 10 States

Area

Arkansas -------

Colorado -------

Ge~rgia--------

Hawaii ---------

Mai.ne----------

Missi.ssippi----

Oregon---------

Pennsylvania- --

South Dakota---

Virginia---- ---

Year of

change

1960

1954

1954

1960

1955

1952

19521

1954

1953

19591

19601

of the United States, 1950-63

Change in minimum gestation period required for registration

From

Although defined for all periods

of gestation, reporting limited

to 20 weeks’ gestation or more

20 weeks’ gestation or more

20 weeks’ gestation or more

No specified gestation

20 weeks’ gestation or more

20 weeks’ gestation or more

20 weeks’ gestation or more

20 weeks’ gestation or more

20 weeks’ gestation or more

All products of conception

20 weeks’ gestation or more

To

All periods of gestation

All products of conception

All products of conception

All periods of gestation

All products of conception

All products of conception

All products of conception

16 weeks’ gestation or more

All products of conception

20 weeks’ gestation or more

All products of conception

lChanged requirement July 1; all other States changed requirement January 1.

11
Table 2. Change in ratio of fetal deatha by week of gestation to all fetal deatha 20 weeka and over,

and the relative change in reporting, when minimum period

lowered: 10 Statea of the United States, 1950-63

of gestation required for registration waa

Arithmetic change in ratio by week of gestation Relative change

in reporting of

fetal deatha

~213Weeksl

Years

prior to

change

Years

after

change &36

weeks

Area

20-27

weeka

28-35

weeks

36

weeks

-1.1

+8.2

+9.0

+1.5

-0.5

-0.4

-0.8

-2.2

-1.7

-2.5

37-39

weeka

-0.1

+9.5

+4.6

+2.6

+0.1

+0.6

+3.1

+1.3

+0.6

+0.4

40

weeks

-3.2

-30.2

-18.3

-9.4

-3.4

-7.7

-7.2

-4.1

-3.7

-7.5

241

weeka

-0.6

+3.5

+1.4

-0.1

+0.1

-0.1

+1.6

+0.8

-1.1

-0.2

Arkanaaa--------

Colorado--------

Georgia---------

Hawaii----------

Maine-----------

Mississippi------

0regon2---------

Penmaylvania----

South Dakota2’~--

Virginia2-------

1956-59

1950-53

1950-53

1952-59

1950-54

1950-51

1950-51

1950-53

1950-52

1960-63

1950-59

1960-63

1954-63

1954-63

1960-63

1955-63

1952-63

1953-63

1954-63

1953-58

1961-63

...

+4.9

+13 .3

+10 .5

+3.0

+3.6

+8.3

+11.2

+5.8

i-7.3

+10 .2

+8.1

+0.1

-4.3

-7.1

+2.6

-0.7

-0.7

-7.8

-1.5

-1.5

-0.8

-2.5

-5.0

-9.0

-3.4

-5.5

-2.9

-7.6

-3.3

-4.3

-5.8

-9.4

-5.6

1.1649

1.0344

1.0469

1.0381

0.8758

1.0311

1.1657

1.0370

1.0371

1.0472

Weighted average . . . +0.7 +2.1 -9.1 +0.8 1.0435

lRelative change = Observed fetal cleat”s after change

Expected fetal cleats after changeY where expected fetal deatha after change =

(adjustment factor for decline in fetal death ratio)x(observed fetal death ratio before change)x(live

births after change).

Qchanged requirement July 1; all other Statea changed requirement January 1.

aData for the perioda 1950-52 and 1959-63 were combined because registration requirements were the

aame. The minimal registration requirement was lowered only for the period 1953-58 (table 1).

with those of 1957-63, andthefollowingarithmetic

changes in the proportion of fetal deaths bygestation period were found:

These changes seem trivial compared with

those for States that lowered their registration

requirements. It would seem then, thatthechange

in the distribution of fetal deaths of 20 weeks or

more that occurred after registration requirements lowered the minimum gestation periodis

real and not merely a function of time.

However, a second question arises. Did the

increase in the-interval 20-27 weeks result from

cases that were formerly unreported or was ita

shifting of fetal deaths within the total group

from one gestation interval to another? Tocheck

this, Dr. Greenberg looked at Upstate New York

again and computed how much the fetal death

ratio had changed during this 14-year period. He

found that it decreased about 10 percentin the7

Change

Period of gestation in

ratio

20-27 weeks ---------------------

28-35 weeks ---------------------

36 weeks and over ---------------

36 weeks ------------------------

37-39 weeks ---------------------

40 weeks ------------------------

41 weeks and over ---------------

+1.6

-0.5

-1.1

-0.5

+1.5

-2.0

-0.2

12
years from the midpoint of 1950-56 to the midpoint of 1957-63. This was the same rate of

decline observed in the total fetal death ratio

for the United States. In order to adjust the decline in the fetal death ratios of the other States

so that a true assessment of the change could

be made, Dr. Greenberg assumed that the period

after the registration change should have a fetal

death ratio lower than that prior to the change

at a rate of about 10 percent for every 7 years.

This gave him an expected fetal death ratio

which, when multiplied by the live births after

the change, resulted in the expected number of

fetal deaths.

Next, he computed a relative increase based

upon the observed fetal deaths during the period

after the change over the expected fetal deaths.

Increases in the ratio of observed to expected

fetal deaths would indicate a real change in the

total number of fetal deaths reported at 20 weeks

or more. Table 2 shows the relative changes.

Nine of the States increased, some as little as 3

percent, and two as much as 16 percent.

Dr. Greenberg concluded that if the European

nations were to lower the minimum reporting

period to less than 28 weeks, the total number of

fetal deaths would probably increase by as much

as 4.35 percent. Since the United States registers

fetal deaths of 20 weeks or more, any comparison

of fetal deaths 28 weeks and over with the

European countries would be biased against the

United States. When the fetal deaths of 28 weeks

and more are examined in order to compare the

United States with some of the European nations,

the fact that the United States has a lower reporting period influences the fetal death ratios.

A second source of variation in the fetal

death ratio arises from differences in determining

the period of gestation. Four registration areas in

the United States base gestation upon the specified

date of last menses, while other areas base it

on the weeks of gestation as reported. When

New York City changed its method of recording

gestation in 1957 and requested that the data of

the first day of the last menstrual period (LMP)

be reported, so that the length of gestation could

be more accurately and consistently calculated,

the fetal death ratio at 20 weeks’ or more gestation increased 24 percent. At the same time,

however, the proportion of “not stated” gestation

periods increased. Discussion brought out the

question of whether other factors added to this

sharp increase, such as the concentrated campaign for better registration which was being

conducted by New York City. However, it was

resolved that this study was concerned with

the immediate effect of the change in reporting the

age of the fetus at a time when the influence

of the campaign for complete registration was

waning. The point to be further studied is that

if data for the United States—New York City to

be specific —can be increased by as much as

one-fourth because of a change in the method

of reporting period of gestation, then how is

gestation period determined in foreign countries

and how does the measurement compare with

that of the United States?

Dr. Greenberg next discussed tabulation

procedures. In the United States, England and

Wales, Scotland, and Norway, first-day mortality includes deaths within 24 hours after birth.

However, in Denmark and the Netherlands, firstday mortality includes only deaths occurring on

the calendar day of birth. In order to appraise the

effect of this tabulation difference, Dr. Greenberg

calculated a separation factor from the distributions of (1) births by hour of birth for a 24-hour

period, and (2) deaths by hour of death among

those infants dying within the first 24 hours

after birth. This separation factor was simply

the percent of babies which die within 24 hours

after birth ,and which do not die on the snme

calendar day of birth. Based on 108,000 live births

in Indiana in 1957 and on the assumption, verified

by North Carolina data, that the distribution of

first-day deaths approximately follows a simple

exponential curve, he estimated the separation

factor to be approximately 22 percent. Otherwise

stated, deaths within 24 hours after birth exceed

deaths occurring on the same calendar day of

birth by about 28 percent.

However, from Norwegian data of 1949-51

and 1959-61 deaths were tabulated for the periods of 24 hours after birth and for the same

calendar day of birth. The two groups of data

indicated that 28.5 percent of the deaths within

the first 24 hours of life did not occur on the

same calehdar day of birth. AS a compromise,

13
Dr. Greenberg felt that

of death under 24 hours

the mortality rates

should be reduced by

25 percent before comparison with data in the

Netherlands and Denmark for first-day mortality. Conversely, deaths under 1 calendar day

for the Netherlands and Denmark should be increased by 33 1/3 percent so that the data for

first-day mortality would be more comparable

to the United States, England and Wales, Norway,

and Scotland.

If ~irst-day mortality is increased in certain

countries, then deaths tabulated as 1-6 days of

age must be decreased correspondingly.

The general conclusion at this point was

that these statistical artifacts were not sufficiently large to account for all the differences in

first-day and first-week mortality between the

United States and the European nations under investigation here.

Next, Dr. Greenberg summarized the incidence and significance of demographic factors such as age of mother, birth order, and

birth weight which were discussed by Dr. van

den Berg in a paper distributed at the conference.

He concluded, in concurrence with Dr. van den

Berg, that although the distributions of live births

by the mother’s age and by birth order are not

favorable in the United States compared with

those in the Western European countries, they do

not account for the total differences in the neonatal mortality rates.

Emphasis was placed on the significantly

higher incidence of low-birth-weight babies in the

United States. While the United States had 8.2

percent live births of 2,500 grams or less in

1963, England and Wales had 6.6 percent. The

Netherlands estimated about 5.5 percent in a

special survey in 1954; and Norway currently

estimates about 5-6 percent. Even though neonatal

mortality of these low-birth-weight babies may

be essentially the same for the various countries,

the fact that the United States appears to have a

greater proportion of these births has a significant effect on its neonatal mortality rate. A look

at registration practices and other factors such

as sex ratio, plurality of birth, illegitimacy, age

of mother, and birth order indicated that they

do not seem to account for the observed international differences in the incidence of low-birthweight infants.

Dr. Greenberg continued the discussion of

low birth weight by considering whether the high

incidence of small babies in the United States was

genetic or cultural. He looked at the data for two

States with high proportions of people of Scandinavian background. Within the two States, Minnesota and North Dakota, he compared the proportion of low-birth-weight babies in the counties

with the highest percentage of Scandinavians to

that of counties with the lowest percentage as

determined by 1960 Census data. In Minnesota,

the Scandinavian background was defined to include Norwegian, Swedish, and Danish stock. In

North Dakota it included Norwegian and Swedish

backgrounds only. In order to obtain meaningful

data, Dr. Greenberg combined data for the years

1955-59. The data showed that the counties with

the highest percentage of Scandinavian stock had

a lower proportion of births of 2,500 grams or

less than did the counties with the lowest proportion of Scandinavian stock (table 3).

Table 3. Percent of live births of 2,500 grams or less: Minnesota and North Dakota,

1955-59

I

Place Nor th Minnesota Dakota

Entire State ------------------------------------------------------- 5.7

Counties with highest proportion of Scandinavian stock ----------- 5.1

Counties with lowest proportion of Scandinavian stock ------------ 5.6

6.3

6.0

6.4

Entire State minus counties with highest proportion of

Scandinavian stock ---------------------------------------------- 5.8 6.3

14
Although these data are not

present an interesting point

gation.

Discussion

Discussion concentrated

conclusive, they do

for further investion the problems of

definition and underregistration. Although the

definition of live birth officially appears to be

the same for the United States and the other

countries involved in the comparison, registration practices do seem to differ. For example,

Denmark, and until recently, England and Wales

used only the criterion of breathing to determine

a live birth, while other countries used the criterion of any signs of life, such as, breathing,

pulsation of umbilical cord, heart beat, movement of voluntary muscles, and so forth.

Based on discussion of underregistration in

the United States and in the Western European

countries, it was concluded that some underregistration and undernotification do indeed exist,

but the extent to which they exist has never been

exactly determined. Dr.. de Haas’ estimated underregistration in the Netherlands to be about 10

percent, but the other European countries felt

that their registration was fairly complete. The

discussion ended here with the general impression

that more study was needed.

Socioeconomic Factors

Dv. Barbara J. van den Berg and

Dr. Arthur J. Lesser

L)r. van den Berg summarized the data available on social class differentials, referring to

studies in the United States which showed a

higher percentage of low-birth-weight babies

among the less favorable socioeconomic classes,

and hence a higher neonatal mortality rate in

these lower social classes. She stated that in the

United States a greater part of the population is

more “severely handicapped by unfavorable conditions than are the people in the Scandinavian

countries and some of the Western

countries.” The indications cited were:

European

unemployment, education, illiteracy, and

housing conditions . . . . Unfavorable economic

conditions of families in the United States

are intensified by the fact that medical care

is not as freely available to them as it is in

some of the European countries and no maternity allowances are given to cover the

extra financial burden of a delivery and no

maternity benefits are given to working pregnant women.

Dr. Lesser emphasized the need for better

medical care facilities for the low-income families. Recognizing the fact that there is a positive

association between family income and infant

mortality, Dr. Lesser described the worsening

situation within cities over 500,000 population

in the. United States. As there has been an influx

of lower income and higher infant mortality risk

groups to the large cities, there has been a

corresponding increase in the number of people

who are dependent upon tax supported medical

services. Compounding the problem is the fact

that this same group seeks prenatal care late in

pregnancy or not at all, and at the same time this

is the group with an excessive rate of low-birthweight babies.

Together with these worsening social factors

is the increasing cost of hospital care, with a

decrease in “the ability of voluntary hospitals to

provide free prenatal and hospital delivery care.

The result has been an increase in the number

of deliveries in’ tax-supported hospitals without

an increase in hospital capacity. These hospitals

have become overcrowded and the length of stay

at the time of delivery in a hospital has been

shortened. Discussion brought out that a new

maternity and infant care program with an appropriation this year of $15 million from Federal

funds has been started to respond to these needs.

Also, there have been an increasing number of

maternal-child-healtn clinics. In order to remedy

the decreasing number of personnel available for

obstetric care, several programs for training

nurses in midwifery have been initiated.

In conclusion, it was mentioned that although it is recognized that many infant deaths

15
occur in the low socioeconomic groups, the

extent to which these deaths affect the total infant mortality rate is not known. Further study

is needed here.

Medical Factors

Dr. William A. Silverman

Dr. Silverman opened the discussion on

medical factors associated with the differential

infant mortality by raising a series of pertinent

and provocative questions. First, he questioned

the adequacy of birth weight as a measure of survival. As a single criterion it tends to obscure

the fact that fetal growth is influenced by many

factors. such as fetal malnutrition or fetal infections. Hence, low-birth- weight babies have

different chances of survival. It would be im -

portant to obtain good standards of fetal growth

so that aberrations could be confidently identified

at birth.

In response to this comment, Dr. Yerushalmy

discussed his study in which a 5-point classification system of both birth weight and gestation

age as an index of fetal maturity was devised

(~able 4). The study showed that in both neonatal

and postneonatal periods mortality increased

from group 5 to group 1; however, the gradient

was more pronounced in the neonatal deaths. In

the low-birth-weight group (3!i-5k pounds), infants

with the shorter gestation period experienced a

higher mortality risk, while those with the longer

gestation period had a greater risk of being congenitally malformed.

Lengthy discussion followed pointing out the

various problems with the criteria of birth weight

and gestation age, partially in response to Dr.

Silverman’s question of whether there truly were

differences in the rate of fetal growth M different

ethnic groups. Points made were that the median

birth weight does vary for different groups and

this consequently would affect the point at which

a baby is considered low in,birth weight. Optimum

birth size (the birth size at which both the baby

and the mother have the greatest chance of survival) varies. For example, in the United States

the optimum size for a white birth is between

3,500-4,000 grams, whereas it is 500 grams less

for a nonwhite infant.

The general conclusion reached at this conference, however, was that, in spite of these

problems, birth weight is certainly the more

important criterion. However, as we are not

dealing with a uniform population when considering

intact survival, additional measurements must be

considered. It was at this point that Dr. Silverman urged that the first day of last menstrual

period be used actively as a more accurate and

consistent measure of gestation age.

Dr. Silverman’s next series of questions

revolved around the problem of mechanisms which

are responsible for major perinatal disorders of

uncertain etiology. Is the incidence of hyaline

membrane disease indeed lower in the Scandinavian countries than in the United States? Is there

an indicator, such as socioeconomic differences,

which could be used to predict the premature

rupture of membranes in various populations?

How much is the distribution of causes affected

Table 4. Index of fetal maturity

Description

Group

Birth weight Period of gestation

3 lbs. 8 oz. or less

; 3 lbs., 9 OZ. -5 lb.8 C)z,

3 lbs. 9 OZ. -5 lb.8 OZ.

: 5 lbs. 9 oz. or more

5 5 lbs, 9 oz. or more

All gestation periods

Under 37 weeks

37 weeks or more

Under 37 weeks

37 weeks or more

16
by the relativity of the diagnoses within the

various colmtries?

These questions led to a discussion of the

growing problem of the etiology of mechanical

suffocation, or the so-called crib death. Several

theories of the true nature of these deaths were

discussed; however, no agreement was reached

about the etiology,

Dr. Silverman next turned to look at the issue

of national differences in medical practices. To

what extent are these practicesrelated to pregnant y outcome and what changes in practices

have occurred during the period under study?

For example, during one recent period in the

United States there was a change in the practice

of the administration of oxygen to low-birthweight infants, and as a result the incidence of

retrolental fibroplasia decreased when oxygen

was given sparingly. What has been happening in

the foreign countries ? How is pregnancy outcome affected by the use of drugs and other

medical methods used to induce labor? How is

the severely involved fetus identified? In ‘short,

there have been marked changes in the policy

of fetal care and delivery over the past decades.

How have these changes affected infant mortality,

and how do they compare internationally?

Dr. Silverman’s questions stimulated others

in response. In reaction to the comment that the

United States is aggressively using active resuscitation, it was surmised that possibly resuscitation of the newborn infant was used more ofien

where” the use of anesthetics and analgesia was

more common, On the other hand, the advisability of such active intervention was questioned.

Another point raised was whether almrtion

acted as a means of preventing some infant

deaths. The Netherlands and Denmark felt that

the number of abortions in a year would not affect

their total infant mortality rate. However, there

is no way to tell now. In order to answer this

question there would have to be a study of the risk

factors related to women having abortions.

These questions were raised not only as an

impetus to spur on discussion, but also as a

means to point out the real difficulty in comparing

international medical practices in connection with

infant mortality. They indicate that additional work

is needed to

international

meaningful.

understand basic practices before

comparisons can be reliable and

Dr. William J. Schull of the University of

Michigan Medical School took time during this

discussion to cite some of his work showing the

effects of heredity on mortality. He stated, in

agreement with Dr. Moriyama. that there is indeed an irreducible, nojzzeJ’o minimum in infant

mortality. One reason is that there will always

be in every culture what may he termed the

iatrogenic death. “Every culture, regardless

of how primitive it has been or how sophisticated

it may become, will have to pay a price for the

administrations of its medicine men. ” Secondly,

a substantial body of biological evidence shows

that a significant portion of infant deaths is of

genetic origin.

Ultimately, the chances of survival in a population are limited by its genetic load— “the

price that any population, human or otherwise.

pays for maintaining genetic variability ’’—and

this load may differ from nation to nation. Dr.

SchuH showed how the “concealed load ,“ the

genetic burden of a population apparent upon

inbreeding, can affect the shape of a population.

The principal source of information on the “concealed load” stems from studies among the children of parents biologically related to one another.

Such studies in Japan in 1956 and 1958-60

showed that increased inbreeding had as a result

(1) smaller babies, (2) increased infant mortality,

but (3) less childlessness.

Dr. Schull also reported that in Hiroshima

and Nagasaki socioeconomic status was lower

as a function of inbreeding. He reported that

school performance of children diminished with

inbreeding; that is to say, the child of biologically

related parents was a poorer performer in all

aspects of school work. Here, Dr. Schull pointed

out that possibly the parents of these children

were of a lower socioeconomic status because

they were inherently poorer illustrations of the

genetic potential of Japan. This may tie in with

the socioeconomic differentials in infant mortality reported by Great Britain.

Finally, Dr. Schull observed that animaI

studies suggest that child survival is apt to be a

function not only of the child’s own genetic constitution, but also of the genetic constitution of

his mother. This was seen in studies with cattle

and swine where mortality increased with inbreeding in the offspring and inbreeding in the

mother, regardless of the father’s background.
SUGGESTIONS FOR FURTHER STUDY

No clear-cut explanations of the significant

international differences in infant mortality

emerged from the discussions of the conference.

It was generally agreed that the international mortality differentials could not be attributed to a

particular statistical artifact or difference in

demographic distributions. However, it could not

be said with any certainty that the cumulative

effects of all these factors would not account for

the difference in mortality.

Although mention was made throughout the

course of the conference of the need for further

study into the various aspects of the infant mor -

tality problem, provision was made in the program

for a specific discussion of needed research on

problems of infant mortality. Suggestions for

further study fall under the following general

headings: (1) basic problems of definitions; (2) registration practices; (3) determinants of perinatal

and infant mortality; and (4) medical factors related to perinatal and infant mortality.

Definitions and Registration Practices

Definitions of live bivtk and fetal death. —AH

of the countries involved in the discussion have

adopted the definitions of live birth and fetal

death recommended by the World Health Organization. An integral part of these definitions is the

criteria of life, namely, breathing or other

evidence of life such as beating of the heart, pulsation of umbilical cord, or definite movement

of voluntary muscles. If a child breathes or shows

any other evidence of life after complete expulsion

or extraction from its mother, even though it be

only momentary, it is required that the event be

registered as a live birth and also as an infant

death. This registration requirement is a change

from that of the past in Sweden, for example, when

breathing was the only criterion for determining

whether an event should be registered as a fetal

death or live birth,

Although no information is available, it is

possible that some small immature infants born

alive are registered as fetal deaths rather than as

a live birth and infant death. These events would

not have any significant effect on the live birth

totals, but could have a marked influence on the

fetal death rate or the infant mortality rate, For

accurate international comparisons, it is important to determine how precisely the criteria of

life are being applied by the attendant at birth in

the registration of live birth and fetal death.

Two approaches were suggested in the study

of this problem. One method was to follow back

on a sample of birth records with a questionnaire

or an interview and obtain from the attendant at

birth information on the criteria which were used

in determining whether a specific event was a live

birth or a fetal death. The other proposal was to

review hospital records in order to determine the

criteria that were applied. The proportion of

deliveries occurring in institutions would be one

of the controlling factors in the choice of methods.

Registration completeness. —There is very

little quantitative information available on registration completeness. The last test of birth registration completeness in the United States was

made in 1950, and showed that 2.1 percent of the

live births were not registered.

There have been no national tests of completeness of death registration for the United

States or for other countries. However, there have

been several local studies in the United States

from which estimates of underregistration have

been made. Using data from records of the

Emergency Maternity and Infant Care Program in

New York City (1943-45), Baumgartner et al. found

that 14 percent of the fetal deaths occurring in the

third trimester of pregnancy were not registered.’]

Schlesinger et al. estimated that in Onondaga

County, New York (1951 -52) about 7 percent of

the fetal deaths of 28 weeks’ or more gestation

were underregistered; however, these particular

data were records from hospitals in an urbanized

county where physicians and hospitals should be

more aware of reporting requirements,4 The total

United States would probably show a higher proportion of underregistered fetal deaths, since

these studies used limited samples. Nevertheless,

these are rather high estimates of underregistration and indicate that national study is needed.

3Baumgartner, L., Wallace, H. M., Landsberg, E., and Pcssin, V.: The inadequacy of routine reporting of fetal deaths,

Am.J.Pub.HeaZth. 39:1549-1552, Dec. 1949.

4Schlesinger, E. R., Beecroft, R. K., Silverman, H. F., and

All away, N. C.: Fetal and early neonatal deaths in Onondaga

county, New York. Pub. Health Rep. 74:1117-1122; Dec. 1959.

18
As more attention is shifted from infant mort:dity to perinatal mortality, the problem of fetal

thmth unclerregistration becomes increasingly

importont, Incomplete reporting of fetal deaths

mokcw occurat eassessrnentof pregnancy wastage

difficult, and hampers investigation of the risk

thctcws influencing perinatal mortality.

l’recise regional orinternational comparison

of fetal and perinatal death rates isalso impaired.

For instance, the United States shows a late fetal

death rate lower than any of the Western European

countries. In 1~62, the fetal death rates for the

Scandinavian countries and the Netherlands were

approximately 15 percent higher than the rate for

the United States. The rate for Great Britain was

about SOpercent higher. Part of these differences

can he attributed to incomplete registration; however, the extent to which this is so needs to be

determined.

(he recommended method of study into the

problem of underregistration was to follow a

cohort of recently married couples to the termination of the first pregnancy, in order to determine

ij :md how the event was registered. Another

possibility is to establish some kind of pregnancy

roster from information from maternity clinics,

and to follow the individuals on the roster through

to the termination of the first pregnancy. It was

suggested that if international comparisons were

to bv made, an international sample should be

selected, and standard forms and protocols be

useL1.

Determinants of Infant Mortality

Birth M@@t. —The incidence of low-birthwcight infants remains largely unknown in countries outside the United States. However, from

special surveys conducted in England and Wales,

the Netherlands, and Norway the estimates seem

to indicate that the United States has a higher

incidence of low-birth-weight babies. Furthermore, in the LTnited States the proportion has

been slowly increasing since 1950.

Tow-birth-weight infants have a much greater

chance Or dying, and hence contribute significantly

m neonatal mortality. Yet, there has been no

nut ionwide e~amination of this problem since

lL]S~, In view of the retardation in the rate of

decline in the infant mortality rate, there is a real

need to obtain national data on the relationship

between birth weight and infant mortality. It was

suggested that one type of study be made by

matching infant death certificates to their respec -

tive birth records. From the birth certificate can

be obtained baseline information such as birth

weight. A study of this type was launched in 1960

in the United States; however, the results of this

study are not yet available.

For purposes of international comparisons,

additional efforts would have to be made since

birth weight does not routinely appear on the

certificates of the foreign countries represented

at this conference, except Denmark, which only

recently added birth weight to its statistical

records. Other sources were suggested from

which data could be drawn for comparison with

vital event records. In areas where prenatal care

records exist in sufficient accuracy and completeness, they could be matched to birth, fetal

death, and infant death certificates. Hospital

records could be used in countries where a large

proportion of deliveries occur in hospitals; and in

instances where midwives attend most of the

deliveries, their records would be a source of

basic information.

Socioeconomic status. —The investigators in

Great Britain have studied the relationship between socioeconomic ,class and infant mortality.

Socioeconomic class, as determined by the ,occupation of the infant’s father, has evidently had a

significant effect on the newborn infant’s prospects of survival. They have found that lower

infant mortality rates occur in the higher classes

and that there is a large gap between the highest

and lowest class. Moreover, the gap has been

widening.

It has been noted in the United States and in

England and Wales that the proportion of lowbirth-weight infants is higher in the lower socioeconomic classes. The question arises whether

this higher proportion is responsible for the

higher infant mortality rate in the lower socioeconomic classes. Or, is socioeconomic status

a factor more important for determining the

level of infant mortality? What are the problems

associated with low- birth-weight (and premature)

neonates born to women in the lower social

classes?

19
In considering the socioeconomic situation,

the problem of adequate measures by which to

define a socioeconomic class was raised. Since

the mother’s background has an important effect

on her reproductive capacity, is the occupation

of the infant’s father a sufficient measure of

social class? Which aspects of social class have

.an important relationship to pregnancy outcome?

Except for local studies in New York State

and California, little recent information has been

collected on the relationship of infant mortality

and social class. More information is needed on

this subject ip the United States.

Ethnic background. —During the conference

there was discussion of the relationship of ethnic

background to pregnancy outcome. It was shown

in a preliminary investigation that in Minnesota

and North Dakota ethnic background may have

an effect on the incidence of low-birth-weight

infants. It has also been indicated that Oriental

infants have lower mortality rates than do white

infants in the United States. However, further

study is needed to determine more exactly the

relationship between infant mortality and ethnic

origin. For instance, how do the infant mortality

rates of different ethnic groups compare by socioeconomic class ? What effect does ethnic background have on the size of the infant at birth?

What influences do immigrant groups have on the

total infant mortality rate?

Medical Factors Related to Infant Mortality

Medical care. —There are important differences in the provision of prenatal and natal care

in the various countries; however, no evidence

was presented to suggest that the level of obstetrical and pediatric care pey se accounts for

a large part of the international differences in

infant mortality. The effects of prenatal, natal,

and neonatal care are important to the study of

infant mortality, yet little is known almut them.

It was suggested that the relationship of prenatal

and obstetric care, including the use of anesthesia,

drugs, and hormones, to pregnancy outcome be

examined. For instance, how are complicated

pregnancies treated, and how does the treatment

relate to the outcome?

Several factors connected with the medical

care of the mother and infant before and after

birth were mentioned as important for study. For

example, women in the lower socioeconomic

strata are less apt to secure early prenatal care,

and at the same time are more likely to experience

poor pregnancy outcome. A study of mothers, integrating information on socioeconomic class

level during their early life as well as at the

time of delivery, and details of prenatal care

would be important to the study of factors correlated with infant mortality.

The incidence of congenital malformations

related to prenatal factors such as drugs taken

during pregnancy and maternal infections could

be inspected in countries with high proportions

of hospital deliveries. Such a study would involve

the integration of prenatal, hospital, and pediatric

records.

The question was raised during discussion

about benefits to be derived from large-scalr

resuscitation of the newborn infant. What is the

relationship of active resuscitation of the neonate

to his well-being? This type of investigation could

best be conducted in the hospital setting.

In the United States the average hospital stay

at the time of delivery is about 4 days; whereas

in Scotland it is about 9 days, 10 days in England

and Wales, and 11-12 days in the Netherlands.

However, the effect of hospital stay on the neonate is unknown. Study of the relationship of

postnatal hospital stay to neonatal mortality

could be conducted by combining birth, hospital,

and death information.

Diseases peculiar to early infancy.- The

neonatal death rate has been leveling off during

the past decade in the United States, yet this

change has not been occurring to the same extent in the European countries. Mortality rates

for the major causes of neonatal death have been

declining; however, the death rate for diseases

peculiar to early infancy has been increasing in

the United States and England and Wales, while

decreasing in the Western European countries.

Part of this increase appears to be IYom the increased reporting of hyaline membrane disease

and respiratory distress syndrome. It was suggested that a detailed investigation of these

diseases be made in order to determine the

meaning of this upward trend.

Incidence of infections. —The postneonatal

mortality rates for many countries have been cut

approximately in half since 1950. However, the

postneonatal mortality rate for the United States

20
has declined very slowly and is now at a relatively high level compared with the rates for

other countries of low mortality.

In 1959-61 over 43 percent of the posmeonatal deaths in the United States were attributed

to infectious diseases. Further reductions in

mortality from this cause are still possible;

however, study of the epidemiological and medical

aspects of infections is urged in order to determine the underlying factors of these diseases.

Major diso~.devs ofwzcertainet iology.-Contern over the increasing frequency of major disorders of uncertain etiology prompted proposal

for thorough study of the incidence of sudden and

unexpected deaths, and mechanical suffocation

in bed or cradle with or without reference to the

certifying physician. What mechanisms are responsible for these disorders?

In 1963 there were 2,998 accidental deaths

among the infants between 28 days and 1 year of

age in the United States. Of these, over 25 percent were ascribed to suffocation in bed or

cradle. These deaths have been under question as

there is evidence that most of these deaths are

not due to accidental mechanical sul%cation, but

are a result of some fulminating infection or

allergic reaction. A study needs to be made which

would include pathological evaluation of the validity of the clinical diagnosis.

In recent years, attention has been called

to the sudden and unexpected deaths. Some of

these deaths appear to be due to respiratory infections. Epidemiological investigations could

be made of these deaths with special attention

to infections among them.

Incidence of nonfatal handicapping conditions. —Improved fetal and infant survival may

result in an increase in infants with handicapping

neurosensory conditions. It was proposed that

examination of this ~ssibility be made. A study

of this relationship would require cooperative

investigations by a number of hospitals with

followup pediatric and psychological examinations.

SUMMARY

In an effort to explain the infant mortality

situation in the United States, a significant number of problem areas in the study of infant and

perinatal mortality were brought into focus at

this 2-day conference. Among the areas considered were the problems in the interpretation

of international data arising from variations in

definitions and in registration and statistical

practices. Risk factors, such as the incidence

of low-birth-weight babies, the socioeconomic

background of the mother, the age of the mother,

the birth order of the infant, and the genetic background of the mother and child were discussed.

Questions were raised about such medical care

aspects as the effect on the infant’s chance of

survival of adequate and inadequate prenatal care,

of hospital stay at the time of birth, and of the

administration of drugs to the mother before and

during parturition. Further questions were raised

about the increasing incidence of perinatal deaths

attributed to diseases of early infancy and to

disorders of uncertain etiology.

There seemed to be no simple, concise

explanation for the leveling off or for the unfavorable position of the infant mortali~ rate in the

United States. No single statistical, demographic,

or medical factor appeared to account for the

international differences observed in the perinatal

and infant mortality rates. However, it was not

possible to assess the relative portion contributed by each factor. In some areas, especially

those associated with medical aspects, data were

not available for the evaluation of their impact

on infant and perinatal mortality.

As the perinatal and infant mortality rates

decrease, the relative effectg of artifacts such as

underregistration of fetal and infant deaths and

differences in definitions and statistical practices

increase. More information on these factors is

needed for the various countries for future comparative studies. Also, data are needed on factors associated with infant mortality such as

socioeconomic conditions, mortality rates among”

low-birth-weight infants, and the effect of prenatal care and obstetrical practices on perinatal

and infant mortality. According y, suggestions

for future research have been made.

Unless some major change in the infant

mortality rates takes place in the United States,

the situation with respect to other countries will

only worsen. It is hoped that serious study will

be given to the problems of perinatal and infant

mortality, and action taken to achieve greater

savings of infant lives.

000

21

* U. S. @OVERNMZNT PRINTING OFFICE - 1S70 - 435.U57 P. 0. 1
Series 1.

Series 2.

Series 3.

Series 4.

SeVies 10.

SeYies 11.

SeYies 12.

SeVies 20.

Sevies 21.

Series 22.

OUTLINE OF REPORT SERIES FOR VITAL AND HEALTH STATISTICS

Public Health Service Publication No. 1000

Progvams and collection procedures. —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.

Reports number 1-4

Rata evaluation and methods Yesearch .—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.

Reports number 1-18

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.

Reports number 1-4

Documents and committee re~orts.—Final reports of major committees concerned with vital and health

statistics, and documents such as recommended model vital registration laws and revised birth nd

death certificates. 4

Reports number 1-3

Data From the Health Interview Survey .—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.

Reports number 1-29

Data From the Health Examirration Survey .—Statistics based on the direct examination, testing, and

measurement of national samples of the population, including the medically defined prevalence of specific diseases, and distributions of the population with respect to various physical and physiological

measurements.

Reports number 1-16

Data Fvom the Health Records .%vuey. —Statistics from records of hospital discharges and statistics

relating to the health characteristics of persons in institutions, and on hospital, medical, nursing, and

personal care received, based on national samples of establishments providing these services and

samples of the residents or patients.

Reports number 1-4

Data on mortality. —Various statistics on mortality other than as included in annual or monthly reportsspecial analyses by cause of death, age, and other demographic variables, also geographic and time

series analyses.

Number 1 wtd 2

Data on natality, mavriage, and divorce. —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.

Reports number 1-9

Data From the National Natality and Mortality .% ’veys. —Statistics on characteristics of births and

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

including such topics as mortality by socioeconomic class, medical experience in the last year of life,

characteristics of pregnancy, etc.

Reports number 1 and 2

For a list of titles of reports published in these series, write to: National Center for Health Statistics

U.S. Public Health Service

Washington, D.C. 20201