TABLE OF CONTENTS

2. BREAST MILK INTAKE .................................................. 2-1

2.1 INTRODUCTION ............................................... 2-1

2.2 STUDIES ON BREAST MILK INTAKE ............................. 2-2

2.2.1 Pao et al., 1980 ............................................ 2-2

2.2.2 Dewey and Lönnerdal, 1983 ................................. 2-2

2.2.3. Butte et al., 1984 .......................................... 2-3

2.2.4. Neville et al., 1988 ......................................... 2-4

2.2.5. Dewey et al., 1991a, b ...................................... 2-4

2.3 STUDIES ON LIPID CONTENT AND FAT INTAKE FROM BREAST MILK

.............................................................. 2-5

2.4 OTHER FACTORS .............................................. 2-7

2.4.1. Population of Nursing Infants ................................ 2-7

2.4.2. Intake Rates Based on Nutritional Status . . . . . . . . . . . . . . . . . . . . . . . 2-8

2.5 RECOMMENDATIONS .......................................... 2-9

2.5.1 Breast Milk Intake ......................................... 2-9

2.5.2 Lipid Content and Lipid Intake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10

2.6 REFERENCES FOR CHAPTER 2 ................................. 2-11
LIST OF TABLES

Table 2-1. Daily Intakes of Breast Milk ......................................... 2-12

Table 2-3. Breast Milk Intake among Exclusively Breast-fed Infants During the First 4 Months

Table 2-6. Lipid Content of Human Milk and Estimated Lipid Intake among Exclusively BreastTable 2-7. Percentage of Mothers Breast-feeding Newborn Infants in the Hospital and Infants at

5 or 6 Months Of Age in the United States in 1989 and 1995, by Ethnic Background and

Table 2-2. Breast Milk ...................................................... 2-12

of Life .............................................................. 2-13

Table 2-4. Breast Milk Intake During a 24-hour Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14

Table 2-5. Breast Milk Intake Estimated by the DARLING Study . . . . . . . . . . . . . . . . . . . . 2-15

fed Infants .......................................................... 2-15

Selected Demographic Variables ......................................... 2-16

Table 2-8. Confidence in Breast Milk Intake Recommendations . . . . . . . . . . . . . . . . . . . . . . 2-17

Table 2-9. Breast Milk Intake Rates Derived from Key Studies . . . . . . . . . . . . . . . . . . . . . . 2-18

Table 2-10. Lipid Intake Rates Derived from Key Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19

Table 2-11. Summary of Recommended Breast Milk And Lipid Intake Rates . . . . . . . . . . . 2-20
1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

2. BREAST MILK INTAKE

2.1 INTRODUCTION 

Breast feeding is known to impart a wide range of benefits to nursing infants, including 

protection against infection, increases in cognitive development, and avoidance of allergies due 

to intolerance to cow’s milk. The American Academy of Pediatrics recommends exclusive 

breast feeding for approximately the first six months and supports the continuation of breast 

feeding for the first year and beyond if desired by the mother and child (APP, 2005). However, 

contaminants may find their way into breast milk of lactating mothers. Lipid soluble chemical 

compounds accumulate in body fat and may be transferred to breast-fed infants in the lipid 

portion of breast milk. Water soluble chemicals may also partition into the aqueous phase and be 

excreted via breast milk. Because nursing infants obtain most (if not all) of their dietary intake 

from breast milk, they are especially vulnerable to exposures to these compounds. Estimating the 

magnitude of the potential dose to infants from breast milk requires information on the milk 

intake rate (quantity of breast milk consumed per day) and the duration (months) over which 

breast-feeding occurs. Information on the fat content of breast milk is also needed for estimating 

dose from breast milk residue concentrations that have been indexed to lipid content. 

Several studies have generated data on breast milk intake. Typically, breast milk intake 

has been measured over a 24-hour period by weighing the infant before and after each feeding 

without changing its clothing (test weighing). The sum of the difference between the measured 

weights over the 24-hour period is assumed to be equivalent to the amount of breast milk 

consumed daily. Intakes measured using this procedure are often corrected for evaporative water 

losses (insensible water losses) between infant weighings (NAS, 1991). Neville et al. (1988) 

evaluated the validity of the test weight approach among bottle-fed infants by comparing the 

weights of milk taken from bottles with the differences between the infants' weights before and 

after feeding. When test weight data were corrected for insensible weight loss, they were not 

significantly different from bottle weights. Conversions between weight and volume of breast 

milk consumed are made using the density of human milk (approximately 1.03 g/mL) (NAS, 

1991). Recently, techniques for measuring breast milk intake using stable isotopes have been 

developed. However, few data based on this new technique have been published (NAS, 1991). 

2-1
1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

Studies among nursing mothers in industrialized countries have shown that intakes 

among infants average approximately 750 to 800 g/day (728 to 777 mL/day) during the first 4 to 

5 months of life with a range of 450 to 1,200 g/day (437 to 1,165 mL/day) (NAS, 1991). Similar 

intakes have also been reported for developing countries (NAS, 1991). Infant birth weight has 

been shown to influence the rate of intake (NAS, 1991). Infants who are larger at birth and/or 

nurse more frequently have been shown to have higher intake rates. 

Key studies on breast milk intake are summarized in the following sections. 

Recommended intake rates are based on the results of these key studies, as described in the 

Exposure Factors Handbook. Relevant data on lipid content and fat intake, breast-feeding 

duration, and the estimated percentage of the U.S. population that breast-feeds are also presented. 

2.2 STUDIES ON BREAST MILK INTAKE 

2.2.1 Pao et al., 1980 

Pao et al. (1980) conducted a study of 22 healthy breast-fed infants to estimate breast 

milk intake rates. Infants were categorized as completely breast-fed or partially breast-fed. 

Breast feeding mothers were recruited through LaLeche League groups. Except for one black 

infant, all other infants were from white middle-class families in southwestern Ohio. The goal of 

the study was to enroll infants as close to one month of age as possible and to obtain records near 

one, three, six, and nine months of age (Pao et al., 1980). However, not all mother/infant pairs 

participated at each time interval. Data were collected for these 22 infants using the test 

weighing method. Records were collected for three consecutive 24-hour periods at each test 

interval. The weight of breast milk was converted to volume by assuming a density of 1.03 

g/mL. Daily intake rates were calculated for each infant based on the mean of the three 24-hour 

periods. Mean daily breast milk intake rates for the infants surveyed at each time interval are 

presented in Table 2-1. These data (Table 2-1) are presented as they are in the report of Pao 

(1980). For completely breast-fed infants, the mean intake rates were 600 mL/day at 1 month of 

age, 833 mL/day at 3 months of age, and 682 mL/day at 6 months of age. Partially breast-fed 

infants had mean intake rates of 485 mL/day, 467 mL/day, 395 mL/day, and <554 mL/day at 1, 3, 

6, and 9 months of age, respectively. Pao et al. (1980) also noted that intake rates for boys in 

both groups were slightly higher than for girls. 

2-2
1 The advantage of this study is that data for both exclusively and partially breast-fed 

2 infants were collected for multiple time periods. Also, data for individual infants were collected 

3 over 3 consecutive days which would account for some individual variability. However, the 

4 number of infants in the study was relatively small. In addition, this study did not account for 

5 insensible weight loss which may underestimate the amount of breast milk ingested. 

6 

7 2.2.2 Dewey and Lönnerdal, 1983 

8 Dewey and Lönnerdal (1983) monitored the dietary intake of 20 breast-fed infants 

9 between the ages of 1 and 6 months. Most of the infants in the study were exclusively breast-fed 

10 (five were given some formula, and several were given small amounts of solid foods after 

11 3 months of age). According to Dewey and Lönnerdal (1983), the mothers were all well 

12 educated and recruited through Lamaze childbirth classes in the Davis area of California. Breast 

13 milk intake volume was estimated based on two 24-hour test weighings per month. Breast milk 

14 intake rates for the various age groups are presented in Table 2-2. Breast milk intake averaged 

15 673, 782, and 896 mL/day at 1, 3, and 6 months of age, respectively. 

16 The advantage of this study is that it evaluated breast-fed infants for a period of 6 months 

17 based on two 24-hour observations per infant per month. However, corrections for insensible 

18 weight loss apparently were not made. Also, the number of infants in the study was relatively 

19 small and the study participants were not representative of the general population. 

20 

21 2.2.3. Butte et al., 1984 

22 Breast milk intake was studied in exclusively breast-fed infants during the first 4 months 

23 of life (Butte et al., 1984). Breastfeeding mothers were recruited through the Baylor Milk Bank 

24 Program in Texas. Forty-five mother/infant pairs participated in the study. However, data for 

25 some time periods (i.e., 1, 2, 3, or 4 months) were missing for some mothers as a result of illness 

26 or other factors. The mothers were from the middle- to upper-socioeconomic stratum and had a 

27 mean age of 28.0 ± 3.1 years. A total of 41 mothers were white, 2 were Hispanic, 1 was Asian, 

28 and 1 was West Indian. Infant growth progressed satisfactorily over the course of the study. 

29 The amount of milk ingested over a 24-hour period was determined by weighing the 

30 infant before and after feeding. To estimate insensible weight loss, the change in weight of a 

31 bottle-fed infant during feeding was compared to the change in weight of the bottle. Based on 

2-3
1 nine successive feedings, insensible weight loss in this infant was estimated to be 3.2 ± 3.1 g. 

2 Test weighing occurred over a 24-hour period for most study participants, but intake among 

3 several infants was studied over longer periods (48 to 96 hours) to assess individual variation in 

4 intake. Mean breast milk intake ranged from 723 g/day (702 mL/day) at 3 months to 751 g/day 

5 (729 mL/day) at 1 month, with an overall mean of 733 g/day (712 mL/day) for the entire study 

6 period (Table 2-3). Intakes were also calculated on the basis of body weight (Table 2-3). Based 

7 on the results of test weighings conducted over 48 to 96 hours, the overall mean variation in 

8 individual daily intake was estimated to be 7.9 ± 3.6%. 

9 The advantage of this study is that data for a larger number of exclusively breast-fed 

10 infants were collected than were collected by Pao et al. (1980). However, data were collected 

11 over a shorter time period (i.e., 4 months compared to 6 months) and day-to-day variability was 

12 not characterized for all infants. 

13 

14 2.2.4. Neville et al., 1988 

15 Neville et al. (1988) studied breast milk intake among 13 infants during the first year of 

16 life. The mothers were all multiparous, nonsmoking, Caucasian women of middle- to 

17 upper-socioeconomic status living in Denver, CO. All women in the study practiced exclusive 

18 breast-feeding for at least 5 months. Solid foods were introduced at mean age of 7 months. 

19 Daily milk intake was estimated by the test weighing method with corrections for insensible 

20 weight loss. Data were collected daily from birth to 14 days, weekly from weeks 3 through 8, 

21 and monthly until the study period ended at 1 year after inception. The estimated breast milk 

22 intakes for this study are listed in Table 2-4. Mean breast milk intakes were 770 g/day (748 

23 mL/day), 734 g/day (713 mL/day), 766 g/day (744 mL/day), and 403 g/day (391 mL/day) at 1, 3, 

24 6, and 12 months of age, respectively. 

25 In comparison to the previously described studies, Neville et al. (1988) collected data on 

26 numerous days over a relatively long time period (12 months) and they were corrected for 

27 insensible weight loss. However, the intake rates presented in Table 2-4 are estimated based on 

28 intake during only a 24-hour period. Consequently, these intake rates are based on short-term 

29 data that do not account for day-to-day variability among individual infants. Also, a smaller 

30 number of subjects was included than in the previous studies. 

31 

2-4
1 2.2.5. Dewey et al., 1991a, b 

2 The Davis Area Research on Lactation, Infant Nutrition and Growth (DARLING) study 

3 was conducted in 1986 to evaluate growth patterns, nutrient intake, morbidity, and activity levels 

4 in infants who were breast-fed for at least the first 12 months of life (Dewey et al., 1991a, b). 

5 Seventy-three infants aged 3 months were included in the study. At subsequent time intervals, the 

6 number of infants included in the study at was somewhat lower as a result of attrition. All 

7 infants in the study were healthy and of normal gestational age and weight at birth, and did not 

8 consume solid foods until after the first 4 months of age. The mothers were highly educated and 

9 of “relatively high socioeconomic status.” 

10 Breast milk intake was estimated by weighing the infants before and after each feeding 

11 and correcting for insensible water loss. Test weighings were conducted over a 4-day period 

12 every 3 months. This decline is associated with the intake of solid food. The results of the study 

13 indicate that breast milk intake declines over the first 12 months of life. Mean breast milk intake 

14 was estimated to be 812 g/day (788 mL/day) at 3 months and 448 g/day (435 mL/day) at 12 

15 months (Table 2-5). Based on the estimated intakes at 3 months of age, variability between 

16 individuals (coefficient of variation ([CV]) = 16.3%) was higher than the average day-to-day 

17 variability ([CV] = 8.9 ± 5.4%) for the infants in the study (Dewey et al., 1991a). 

18 The advantages of this study are that data were collected over a relatively long-time 

19 (4 days) period at each test interval which would account for some day-to-day infant variability, 

20 and corrections for insensible water loss were made. 

21 

22 2.3 STUDIES ON LIPID CONTENT AND FAT INTAKE FROM BREAST MILK 

23 Human milk contains over 200 constituents including lipids, various proteins, 

24 carbohydrates, vitamins, minerals, and trace elements as well as enzymes and hormones. The 

25 lipid content of breast milk varies according to the length of time that an infant nurses, and 

26 increases from the beginning to the end of a single nursing session (NAS, 1991). The lipid 

27 portion accounts for approximately 4% of human breast milk (39± 4.0 g/L) (NAS, 1991). This 

28 value is supported by various studies that evaluated lipid content from human breast milk. 

29 Several studies also estimated the quantity of lipid consumed by breast-feeding infants. These 

30 values are appropriate for performing exposure assessments for nursing infants when the 

2-5
1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

contaminant(s) have residue concentrations that are indexed to the fat portion of human breast 

milk. 

2.3.1 Butte et al., 1984 

Butte et al. (1984) analyzed the lipid content of breast milk samples taken from women 

who participated in a study of breast milk intake among exclusively breast-fed infants. The study 

was conducted with over 40 women during a 4-month period. The mean lipid content of breast 

milk at various infants’ ages is presented in Table 2-6. The overall lipid content for the 4-month 

study period was 34.3 ± 6.9 mg/g (3.4%). Butte et al. (1984) also calculated lipid intakes from 

24-hour breast milk intakes and the lipid content of the human milk samples. Lipid intake was 

estimated to range from 23.6 g/day (3.8 g/kg-day) to 28.0 g/day (5.9 g/kg-day). 

The number of women included in this study was small, and these women were selected 

primarily from middle to upper socioeconomic classes. Thus, data on breast milk lipid content 

from this study may not be entirely representative of breast milk lipid content among the U.S. 

population. Also, these estimates are based on short-term data, and day-to-day variability was 

not characterized. 

2.3.1 Maxwell and Burmaster, 1993 

Maxwell and Burmaster (1993) used a hypothetical population of 5000 infants between 

birth and 1 year of age to simulate a distribution of daily lipid intake from breast milk. The 

hypothetical population represented both bottle-fed and breast-fed infants aged 1 to 365 days. A 

distribution of daily lipid intake was developed, based on data in Dewey et al. (1991b) on breast 

milk intake for infants at 3, 6, 9, and 12 months and breast milk lipid content, and survey data in 

Ryan et al. (1991) on the percentage of breast-fed infants under the age of 12 months (i.e., 

approximately 22%). A model was used to simulate intake among 1113 of the 5000 infants that 

were expected to be breast-fed. The results of the model indicated that lipid intake among 

nursing infants under 12 months of age can be characterized by a normal distribution with a mean 

of 26.8 g/day and a standard deviation of 7.4 g/day (Table 2-7). The model assumes that nursing 

infants are completely breast-fed and does not account for infants who are breast-fed longer than 

1 year. Based on data collected by Dewey et al. (1991b), Maxwell and Burmaster (1993) 

estimated the lipid content of breast milk to be 36.7 g/L at 3 months (35.6 mg/g or 3.6%), 39.2 

2-6
1 g/L at 6 months (38.1 mg/g or 3.8%), 41.6 g/L at 9 months (40.4 mg/g or 4.0%), and 40.2 g/L at 

2 12 months (39.0 mg/g or 3.9%). 

3 The advantage of this study is that it provides a “snapshot” of daily lipid intake from 

4 breast milk for breast-fed infants. These results are, however, based on a simulation model and 

5 there are uncertainties associated with the assumptions made. The estimated mean lipid intake 

6 rate represents the average daily intake for nursing infants under 12 months of age. These data 

7 are useful for performing exposure assessments when the age of the infant cannot be specified 

8 (i.e., 3 months or 6 months). Also, because intake rates are indexed to the lipid portion of the 

9 breast milk, they may be used in conjunction with residue concentrations indexed to fat content. 

10 However, the study did not generate “new” data. A reanalysis of previously reported data on 

11 breast milk intake and breast milk lipid intake were provided. 

12 

13 2.4 OTHER FACTORS 

14 Other factors associated with breast milk intake include: the frequency of breast-feeding 

15 sessions per day, the duration of breast-feeding per event, the duration of breast-feeding during 

16 childhood, and the magnitude and nature of the population that breast-feeds (i.e., socioeconomic 

17 factors, ethnicity, etc.). 

18 

19 2.4.1. Population of Nursing Infants 

20 According to the National Academy of Sciences (NAS), the percentage of breast-feeding 

21 women has changed dramatically over the years (NAS, 1991). The Ross Products Division of 

22 Abbott Laboratories conducted a large national mail survey in 1995 to determine patterns of 

23 breast feeding during the first 6 months of life. The Ross Laboratory Mothers’s Survey was first 

24 developed in 1955 and has been expanded to include many more infants. Before 1991, the 

25 survey was conducted on a quarterly basis, and approximately 40,000 to 50,000 questionnaires 

26 were mailed each quarter (Ryan, 1997). Beginning in 1991, the survey was conducted monthly; 

27 35,000 were mailed each month. Over time, the response rate has been consistently in the range 

28 of 50 ± 5%. In 1989 and 1995, 196,000 and 720,000 questionnaires were mailed, respectively. 

29 Ryan (1997) reported rates of breast-feeding through 1995 and compared them with those in 

30 1989. 

2-7
1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

The survey demonstrates recent increases in both the initiation of breast-feeding and 

continued breast-feeding at 6 months of age. Table 2-7 presents the percent of breast-feeding in 

hospitals and at 6 months of age by selected demographic characteristics. In 1995, the incidence 

of breast-feeding at birth and at 6 months for all infants was approximately 60% and 22 %, 

respectively. The largest increases in the initiation of breast-feeding between 1989 and 1995 

occurred among women who (1) were Black, were less than 25 years of age, earned less than 

$10,000 per year, had no more than grade school education, and were living in the South Atlantic 

region of the U.S.; (2) had infants of low birth weight; (3) were employed full time outside the 

home at the time they received the survey; and (4) participated in the Women, Infants, and 

Children program (WIC). In 1995, as in 1989, the initiation of breast-feeding was highest among 

women who were greater than 35 years of age, earned more than $25,000 per year, and were 

college educated; women who did not participate in the WIC program; and women who were 

living in the Mountain and Pacific regions of the U.S. 

Data on the actual length of time that infants continue to breast-feed beyond 5 or 6 

months are limited (NAS, 1991). However, Maxwell and Burmaster (1993) estimated that 

approximately 22 percent of infants under 1 year of age are breast-fed. This estimate is based on 

a reanalysis of survey data in Ryan et al. (1991) collected by Ross Laboratories (Maxwell and 

Burmaster, 1993). 

2.4.2. Intake Rates Based on Nutritional Status 

Information on differences in the quality and quantity of breast milk on the basis of ethnic 

or socioeconomic characteristics of the population is limited. Lönnerdal et al. (1976) studied 

breast milk volume and composition (nitrogen, lactose, proteins) among underprivileged and 

privileged Ethiopian mothers. No significant differences were observed between the data for 

these two groups. Similar data were observed for well-nourished Swedish mothers. Lönnerdal et 

al. (1976) stated that these results indicate that breast milk quality and quantity are not affected 

by maternal malnutrition. However, Brown et al. (1986a, b) noted that the lactational capacity 

and energy concentration of marginally-nourished women in Bangladesh were “modestly less 

than in better nourished mothers.” Breast milk intake rates for infants of marginally-nourished 

women in this study were 690 ± 122 g/day at 3 months, 722 ± 105 g/day at 6 months, and 719 ± 

119 g/day at 9 months of age (Brown et al., 1986a). Brown et al. (1986a) observed that breast 

2-8
1 milk from women with larger measurements of arm circumference and triceps skinfold thickness 

2 had higher concentrations of fat and energy than mothers with less body fat. Positive correlations 

3 between maternal weight and milk fat concentrations were also observed. These results suggest 

4 that milk composition may be affected by maternal nutritional status. 

5 

6 2.5 RECOMMENDATIONS 

7 The studies described in this section were used in selecting recommended values for 

8 breast milk intake, fat content and fat intake, and other related factors. Although different survey 

9 designs, testing periods, and populations were utilized by the studies to estimate intake, the mean 

10 and standard deviation estimates reported in these studies are relatively consistent. There are, 

11 however, limitations with the data. With the exception of Butte (1984), data were not presented 

12 on a body weight basis. This is particularly important since intake rates may be higher on a body 

13 weight basis for younger infants. Also, the data used to derive the recommendations are over 15 

14 years old and the sample size of the studies was small. Other subpopulations of concern such as 

15 mothers highly committed to breast feeding— sometimes for periods longer than 1 year— may 

16 not be captured by the studies presented in this chapter. Further research is needed to identify 

17 these subgroups and to get better estimates of breast milk intake rates. Table 2-8 presents the 

18 confidence rating for breast milk intake recommendations. 

19 

20 2.5.1 Breast Milk Intake 

21 The breast milk intake rates for nursing infants that have been reported in the studies 

22 described in this section are summarized in Table 2-9. It should be noted that the decrease in 

23 breast milk intake with age is likely a result of complementary foods being introduced as the 

24 child grows and not necessarily a decrease in total energy intake. In order to conform to the new 

25 standardized age groupings used in this Handbook (see Chapter 1), data from Pao et a. (1980), 

26 Dewey and Lönnerdal (1983), Butte et al. (1984), Neville et al. (1988), Dewey et al. (1991a), and 

27 Dewey et al. (1991b) were compiled for each month of the first year of life. For some months 

28 multiple studies were available; for others only one study was available. Weighted means were 

29 calculated for each age in months. Upper percentiles were calculated as the midpoint of the range 

30 of upper percentiles of the studies available for each age in months. These month-by-month 

31 intakes were composited to yield intakes for the standardized age groups by taking an 

2-9
1

2

3

4

5

6

7

8

9

10

11

unweighted average, assuming that in the general population, each age (e.g., 3, 4, and 5 months) 

is equally represented. 

2.5.2 Lipid Content and Lipid Intake 

Recommended lipid intake rates are presented in Table 2-10. The table parallels the 

breast milk intake table (Table 2-9). Figures were calculated assuming a lipid content of 4% 

(Butte et al.,1984; NAS, 1991; Maxwell and Burmaster, 1993). An exception to this method was 

employed in the case of the Butte et al. (1984) study, where lipid intakes were provided in the 

study. The values from the study were used in place of the estimated lipid intakes. 

2-10
5

10

15

20

25

30

35

40

45

50

1 2.6 REFERENCES FOR CHAPTER 2 

2 

3 

4 

APP (2005) Breast feeding and the use of human milk. Policy Statement. Pediatrics Vol. 115 No. 2 February 2005, 

pp. 496-506 available on line at http://aappolicy.aappublications.org/cgi/content/full/pediatrics;115/2/496 

6 

7 

8 

Brown, K.H.; Akhtar, N.A.; Robertson, A.D.; Ahmed, M.G. (1986a) Lactational capacity of marginally nourished 

mothers: relationships between maternal nutritional status and quantity and proximate composition of milk. 

Pediatrics. 78: 909-919. 

9 

11 

12 

Brown, K.H.; Robertson, A.D.; Akhtar, N.A. (1986b) Lactational capacity of marginally nourished mothers: infants' 

milk nutrient consumption and patterns of growth. Pediatrics. 78: 920-927. 

13 

14 

Butte, N.F.; Garza, C.; Smith, E.O.; Nichols, B.L. (1984) Human milk intake and growth in exclusively breast-fed 

infants. Journal of Pediatrics. 104:187-195. 

16 

17 

18 

Dewey, K.G.; Lönnerdal, B. (1983) Milk and nutrient intake of breast-fed infants from 1 to 6 months:relation to 

growth and fatness. Journal of Pediatric Gastroenterology and Nutrition. 2:497-506. 

19 Dewey, K.G.; Heinig, J.; Nommsen, L.A.; Lönnerdal, B. (1991a) Maternal versus infant factors related to breast 

21 

milk intake and residual volume: the DARLING study. Pediatrics. 87:829-837. 

22 

23 

24 

Dewey, K.G.; Heinig, J.; Nommsen, L.; Lönnerdal, B. (1991b) Adequacy of energy intake among breast-fed infants 

in the DARLING study: relationships to growth, velocity, morbidity, and activity levels. The Journal of 

Pediatrics. 119:538-547. 

26 

27 

28 

Lönnerdal, B.; Forsum, E.; Gebre-Medhim, M.; Hombraes, L. (1976) Breast milk composition in Ethiopian and 

Swedish mothers: lactose, nitrogen, and protein contents. The American Journal of Clinical Nutrition. 29:1134­

1141. 

29 

31 

32 

Maxwell, N.I.; Burmaster, D.E. (1993) A simulation model to estimate a distribution of lipid intake from breast 

milk during the first year of life. Journal of Exposure Analysis and Environmental Epidemiology. 3:383-406. 

33 

34 

National Academy of Sciences (NAS). (1991) Nutrition during lactation. Washington, DC. National Academy 

Press. 

36 

37 

38 

Neville, M.C.; Keller, R.; Seacat, J.; Lutes, V.; Neifert, M.; et al. (1988) Studies in human lactation: milk volumes 

in lactating women during the onset of lactation and full lactation. American Journal of Clinical Nutrition. 

48:1375-1386. 

39 

41 

Pao, E.M.; Hines, J.M.; Roche, A.F. (1980) Milk intakes and feeding patterns of breast-fed infants. Journal of the 

American Dietetic Association. 77:540-545. 

42 

43 

44 

Ryan, A.S.; Rush, D.; Krieger, F.W.; Lewandowski, G.E. (1991) Recent declines in breastfeeding in the United 

States, 1984-1989. Pediatrics. 88:719-727. 

46 

47 

48 

Ryan, A.S. (1997) The resurgence of breastfeeding in the United States. Pediatrics. 99(4):e12. 

http://www.pediatrics.org/cqi/content/full/99/4/e12. 

49 

51 

52 

2-11
Table 2-1. Daily Intakes of Breast Milk 

Age Number of Infants 

Intake 

Mean ± SD 

(mL/day) a 

Intake Range 

(mL/day) 

Completely Breast-fed 

1 month 

3 months 

6 months 

11 

2 

1 

600 ± 159 

833 

682 

426 - 989 

645 - 1,000 

616 - 786 

Partially Breast-fed 

1 month 

3 months 

6 months 

9 months 

4 

11 

6 

3 

485 ± 79 

467 ± 100 

395 ± 175 

<554 

398 - 655 

242 - 698 

147 - 684 

451 - 732 

a

Data expressed as mean ± standard deviation. 

Source: Pao et al., 1980. 

Table 2-2. Breast Milk Intakes for infants aged 1 to 6 months 

Age 

(months) 

Number of Infants 

Intake 

Mean ± SD 

(mL/day) 

Intake Range 

(mL/day) 

1 16 673 ± 192 341-1003 

2 19 756 ± 170 449-1055 

3 16 782 ± 172 492-1053 

4 13 810 ± 142 593-1045 

5 11 805 ± 117 554-1045 

6 11 896 ± 122 675-1096 

Source: Dewey and Lönnerdal, 1983 

2-12
Table 2-3. Breast Milk Intake among Exclusively Breast-fed Infants During the First 4 Months of Life 

Age 

(months) Number of Infants 

Intake (g/day) Intake (g/kg-day) Body Weighta 

(kg) 

Mean ± SD Mean ± SD 

1 37 751.0 ± 130.0 159.0 ± 24.0 4.7 

2 40 725.0 ± 131.0 129.0 ± 19.0 5.6 

3 37 723.0 ± 114.0 117.0 ± 20.0 6.2 

4 41 740.0 ± 128.0 111.0 ± 17.0 6.7 

a

Calculated by dividing breast milk intake (g/day) by breast milk intake (g/kg-day). 

Source: Butte et al., 1984 

2-13
Table 2-4. Breast Milk Intake During a 24-hour Period 

Age 

(days) Number of Infants 

Intake ( g/day) Intake by age category 

(g/d)b 

Mean ± SD Range 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

14 

21 

28 

6 

9 

10 

10 

11 

9 

7 

8 

9 

9 

8 

9 

10 

13 

44 ± 71 

182 ± 86 

371 ± 153 

451 ± 176 

498 ± 129 

508 ± 167 

573 ± 167 

581 ± 159 

580 ± 76 

589 ± 132 

615 ± 168 

653 ± 154 

651 ± 84 

770 ± 179 

-31-149 a 

44-355 

209-688 

164-694 

323-736 

315-861 

406-842 

410-923 

470-720 

366-866 

398-934 

416-922 

554-786 

495-1144 

526 ± 227 

35 

42 

49 

56 

12 

12 

10 

12 

668 ± 117 

711 ± 111 

709 ± 115 

694 ± 98 

465-930 

554-896 

559-922 

556-859 

699 ± 108 

90 10 734 ± 114 613-942 734 ± 114 

120 12 711 ± 100 570-847 711 ± 100 

150 12 838 ± 134 688-1173 838 ± 134 

180 13 766 ± 121 508-936 766 ± 121 

210 12 721 ± 154 486-963 721 ± 154 

240 9 622 ± 210 288-1002 622 ± 210 

270 12 618 ± 220 223-871 618 ± 220 

300 11 551 ± 234 129-894 551 ± 234 

330 8 554 ± 240 120-860 554 ± 240 

360 8 403 ± 250 65-770 403 ± 250 

a

Negative value due to insensible weight loss correction. b

Multiple data sets were combined by producing simulated data sets fitting the known mean and SD for each age,

compositing the data sets to correspond to age groups of 0 to <1 month and 1 to <2 months, and calculating new means and

SD’s on the composited data.

SD = standard deviation. 

Source: Neville et al., 1988 

2-14
Table 2-5. Breast Milk Intake Estimated by the DARLING Study 

Age

 (months) 

Number of Infants 

Intake (g/day) 

Mean ± SD 

3 73 812 ± 133 

6 60 769 ± 171 

9 50 646 ± 217 

12 42 448 ± 251 

Source: Dewey et al., 1991b 

Table 2-6. Lipid Content of Human Milk and Estimated Lipid Intake among Exclusively Breast-fed Infants 

Age 

(months) 

Number 

of 

Observations 

Lipid Content 

(mg/g) Lipid 

Content % a 

Lipid 

Intake 

(g/day) 

Mean ± SD 

Lipid 

Intake 

(g/kg-day) 

Mean Mean ± SD ± SD 

1 

2 

3 

4 

37 

40 

37 

41 

36.2 ± 7.5 

34.4 ± 6.8 

32.2 ± 7.8 

34.8 ± 10.8 

3.6 

3.4 

3.2 

3.5 

28.0 ± 8.5 

25.2 ± 7.1 

23.6 ± 7.2 

25.6 ± 8.6 

5.9 ± 1.7 

4.4 ± 1.2 

3.8 ± 1.2 

3.8 ± 1.3 

a

Percents calculated from lipid content reported in mg/g. 

Source: Butte, et al., 1984 

2-15
Table 2-7. Percentage of Mothers Breast-feeding Newborn Infants in the Hospital and Infants at 5 or 6 Months Of 

Age in the United States in 1989 and 1995, by Ethnic Background and Selected Demographic Variables 

Percentage of Mothers Breast-Feeding

Characteristic In Hospital At 6 Months 

a a 1989 1995 Change 1989 1995 Change 

All Infants 52.2 59.7 14.4 18.1 21.6 19.3 

White 58.5 64.3 9.9 21.0 24.1 14.8 

Black 23.0 37.0 60.9 6.4 11.2 75.0 

Hispanic 48.4 61.0 26.0 13.9 19.6 41.0 

Maternal Age (years) 

<20 30.2 42.8 41.7 5.6 9.1 62.5 

20-24 4.2 52.6 16.4 11.5 14.6 27.0 

25-29 58.8 63.1 7.3 21.1 22.9 8.5 

30-34 65.5 68.1 4.0 29.3 29.0 (1.0)b 

35+ 66.5 70.0 5.3 34.0 33.8 (0.6)b 

Total Family Income 

<$10,000 31.8 41.8 31.4 8.2 11.4 39.0 

$10,000 - $14,999 47.1 51.7 9.8 13.9 15.4 10.8 

$15,000 - $24,999 54.7 58.8 7.5 18.9 19.8 4.8 

$25,000 66.3 70.7 6.6 25.5 28.5 11.8 

Maternal Education 

Grade School 31.7 43.8 38.2 11.5 17.1 48.7 

High School 42.5 49.7 16.9 12.4 15.0 21.0 

College 70.7 74.4 5.2 28.8 31.2 8.3 

Maternal Employment 

Employed Full Time 50.8 60.7 19.5 8.9 14.3 60.7 

Employed Part Time 59.4 63.5 6.9 21.1 23.4 10.9 

Not Employed 51.0 58.0 13.7 21.6 25.0 15.7 

Birth Weight 

Low (#2,500 g) 36.2 47.7 31.8 9.8 12.6 28.6 

Normal 53.5 60.5 13.1 18.8 22.3 18.6 

Parity 

Primiparous 52.6 61.6 17.1 15.1 19.5 29.1 

Multiparous 51.7 57.8 11.8 21.1 23.6 11.8 

WIC Participationc 

Participant 34.2 46.6 36.3 8.4 12.7 51.2 

Nonparticipant 62.9 71.0 12.9 23.8 29.2 22.7 

U.S. Census Region 

New England 52.2 61.2 17.2 18.6 22.2 19.4 

Middle Atlantic 47.4 53.8 13.5 16.8 19.6 16.7 

East North Central 47.6 54.6 14.7 16.7 18.9 13.2 

West North Central 55.9 61.9 10.7 18.4 21.4 16.3 

South Atlantic 43.8 54.8 25.1 13.7 18.6 35.8 

East South Central 37.9 44.1 16.4 11.5 13.0 13.0 

West South Central 46.0 54.4 18.3 13.6 17.0 25.0 

Mountain 70.2 75.1 7.0 28.3 30.3 7.1 

Pacific 70.3 75.1 6.8 26.6 30.9 16.2 

a The percent change was calculated using the following formula: % breastfed in 1984 - % breastfed in 1989 / % breastfed in 

1984. 

b Figures in parentheses indicate a decrease in the rate of breastfeeding from 1989 to 1995. 

WIC indicates Women, Infants, and Children supplemental food program. 

Source: Ryan, 1997 

2-16

c 
Table 2-8. Confidence in Breast Milk Intake Recommendations 

Considerations Rationale Rating 

Study Elements 

Level of peer review All key studies are from peer reviewed literature. High 

Accessibility Papers are widely available from peer reviewed journals. High 

Reproducibility Methodology used was clearly presented. High 

Focus on factor of interest The focus of the studies was on estimating breast milk intake. High 

Data pertinent to U.S. Subpopulations of the U.S. were the focus of all the key studies. High 

Primary data All the studies were based on primary data. High 

Currency Studies were conducted between 1980-1997. MediumHigh 

Adequacy of data collection 

period 

Infants were not studied long enough to fully characterize day to day 

variability. With the exception of Neville et al. (1988), the 

measurements were made in frequency (e.g., once a month) and the 

data may not represent the potential first year of lactation (both for 

less than 1 month of age and for longitudinal measurements of more 

than 6 months). 

Medium 

Validity of approach Methodology uses changes in body weight as a surrogate for total 

ingestion. This is the best methodology there is to estimate breast 

milk ingestion; however, because there are limitations to this 

approach, the confidence rating was judged to be low. Mothers were 

instructed in the use of infant scales to minimize measurement errors. 

Three out of the 5 studies corrected data for insensible water loss. 

Low 

Study size The sample sizes used in the key studies were fairly small (range 13­

73). 

Low 

Representativeness of the 

population 

Population are representative of the general mother-infant pair 

population. 

High 

Characterization of variability Not very well characterized. Infants under 1 month not captured, 

mothers committed to breast feeding over 1 year not captured. 

Low 

Lack of bias in study design 

(high rating is desirable) 

Bias in the studies was not characterized. Two out of 5 studies 

corrected for insensible water loss. 

Low 

Measurement error All mothers were well educated and trained in the use of the scale 

which helped minimize measurement error. Not correcting for 

insensible water loss may underestimate intake. Mothers selected for 

the studies were volunteers; therefore response rate does not apply. 

Population studied may introduce some bias in the results (see 

above). 

Medium 

Other Elements 

Number of studies There are 5 key studies. Medium 

Agreement between researchers There is good agreement among researchers. High 

Overall Rating Studies were well designed. Results were consistent. Sample size 

was fairly low. Variability cannot be characterized due to limitations 

in data collection period. 

Medium 

2-17
Table 2-9. Breast Milk Intake Rates Derived from Key Studies 

Age 

(months) 

Number 

of 

Children 

Mean 

Intake 

(mL/day) 

Upper 

Percentile 

Consumption 

Reference 

Weighted Mean Intake 

and Upper Percentile Consumptionb 

(across all Key Studies) 

(mL/day) 

(mL/day)a 

individual age composite ages 

Mean Upper Meand Upper 

0 128 511 952 Neville et al., 1988 511 952 511 952 

1 

11 

37 

13 

16 

600 

729 

679 

673 

918 

982 

888 

1057 

Pao et al., 1980 

Butte et al., 1984 

Neville et al., 1988 

Dewey and Lönnerdal, 1983 

687 973 

703 992 

2 10 713 934 Neville et al., 1988 720 1015 

19 756 1096 Dewey and Lönnerdal, 1983 

40 704 958 Butte et al., 1984 

2 833 —c Pao et al., 1980 

37 702 923 Butte et al., 1984 757 1005 

3 12 690 884 Neville et al., 1988 

16 

73 

782 

788 

1126 

1047 

Dewey and Lönnerdal, 1983 

Dewey et al., 1991b 

761 1005 

4 12 814 1074 Neville et al., 1988 754 1031 

13 810 1094 Dewey and Lönnerdal, 1983 

41 718 967 Butte et al., 1984 

5 13 744 979 Neville et al., 1988 772 1009 

11 805 1039 Dewey and Lönnerdal, 1983 

1 682 —c Pao et al., 1980 

12 700 999 Neville et al., 1988 759 1070 

6 11 

60 

896 

747 

1140 

1079 

Dewey and Lönnerdal, 1983 

Dewey et al., 1991b 

584 1009 

7 9 604 1012 Neville et al., 1988 604 1012 

8 12 600 1027 Neville et al., 1988 600 1027 

9 11 535 989 Neville et al., 1988 610 1019 

50 627 1049 Dewey et al., 1991b 

10 8 538 1004 Neville et al., 1988 538 1004 

11 8 391 877 Neville et al., 1988 391 877 

12 42 435 922 Dewey et al., 1991a; 1991b 435 922 435 922 

a 

Upper percentile is reported (mean plus 2 standard deviations), except as noted. b Middle of the range.

Standard deviations and upper percentiles not calculated for small sample sizes. d Calculated as an unweighted mean, assuming that in the general population, each 

age (e.g., 3,4, and 5 months) is equally represented. 

2-18

c 
Table 2-10. Lipid Intake Rates Derived from Key Studies 

Age 

(months) 

Number 

of 

Children 

Mean 

Intake 

(mL/day) 

Upper Percentile 

Consumption 

(mL/day)a 

Reference 

Weighted Mean Intake 

and Upper Percentile Consumptionb 

(across all Key Studies) 

(mL/day) 

individual age composite ages 

Mean Upper Meand Upper 

0 128 20.4 38.1 Neville et al., 1988 20 38 20 38 

1 

11 

37 

13 

16 

24.0 

27.2 

27.2 

26.9 

36.7 

43.7 

35.5 

42.3 

Pao et al., 1980 

Butte et al., 1984 

Neville et al., 1988 

Dewey and Lönnerdal, 1983 

27 

40 

27 40 

2 10 28.5 37.4 Neville et al., 1988 27 41 

19 30.2 43.8 Dewey and Lönnerdal, 1983 

40 24.5 38.3 Butte et al., 1984 

2 33.3 —c Pao et al., 1980 29 40 

37 22.9 36.9 Butte et al., 1984 

3 12 27.6 35.4 Neville et al., 1988 

16 

73 

31.3 

31.5 

45.0 

41.9 

Dewey and Lönnerdal, 1983 

Dewey et al., 1991b 

29 40 

4 12 32.6 43.0 Neville et al., 1988 28 43 

13 32.4 43.8 Dewey and Lönnerdal, 1983 

41 24.9 41.6 Butte et al., 1984 

5 13 29.8 39.2 Neville et al., 1988 31 40 

11 32.2 41.6 Dewey and Lönnerdal, 1983 

1 27.3 —c Pao et al., 1980 30 43 

12 28.0 40.0 Neville et al., 1988 

6 11 

60 

35.8 

29.9 

45.6 

43.2 

Dewey and Lönnerdal, 1983 

Dewey et al., 1991b 

23 40 

7 9 24.2 40.5 Neville et al., 1988 24 40 

8 12 24.0 41.1 Neville et al., 1988 24 41 

9 11 21.4 39.6 Neville et al., 1988 24 41 

50 25.1 42.0 Dewey et al., 1991b 

10 8 21.5 40.2 Neville et al., 1988 22 40 

11 8 15.6 35.1 Neville et al., 1988 16 35 

12 42 17.4 36.9 Dewey et al., 1991a; 1991b 17 37 17 37 

a 

Upper percentile is reported (mean plus 2 standard deviations), except as noted. b Middle of the range.

Standard deviations and upper percentiles not calculated for small sample sizes. d Calculated as an unweighted mean, assuming that in the general population, each age 

(e.g., 3,4, and 5 months) is equally represented. e Calculated from breast milk intake assuming a lipid content of 4% (NAS, 1991; Butte et 

al., 1984, and Maxwell and Burmaster, 1993). EXCEPT data from Butte et al. (1984), 

where lipid data were provided. 

2-19

c 
Table 2-11. Summary of Recommended Breast Milk And Lipid Intake Rates 

Age 

Breast Milk Intake, mL/day Lipid Intake , mL/day a 

Mean Upper Percentile Mean Upper Percentile 

birth to < 1 month 511 952 20 30 

1 to < 3 months 703 992 27 40 

3 to < 6 months 761 1005 29 40 

6 to < 12 months 584 1009 23 40 

birth to 1 year 642 973 25 39 

a

The recommended value for the lipid content of breast milk is 4.0 percent. See Section 2.5.2. b

Middle of the range of upper percentile values. 

2-20