Because of the recognized benefits of exclusive breastfeeding,1–7 the American Academy of Pediatrics and the World Health Organization strongly encourage exclusive breastfeeding for the first 6 months of life.7,8 Unfortunately, national goals for exclusive breastfeeding in the United States are not yet established, at least in part because of a lack of data.
The Third National Health and Nutrition Examination Survey (NHANES III) sample is nationally representative and particularly valuable in providing data on exclusive breastfeeding. We used NHANES III data to examine the prevalence of exclusive breastfeeding among US infants to obtain baseline data for program evaluation and public health policymaking.
METHODS
NHANES, a series of cross-sectional surveys conducted by the National Center for Health Statistics (NCHS), is designed to produce nationally representative data on the civilian, noninstitutionalized US population. Details on the study's design and methods are described elsewhere.9 NHANES III, conducted between 1988 and 1994 in participants aged 2 months and older, was divided into phases I (1988–1991) and II (1991–1994). Surveys from phases I and II included questions regarding initiation and duration of breastfeeding, whereas only the phase II survey included a question on supplements to breast milk.
NCHS collected the breastfeeding data by means of a household youth questionnaire during a home interview with a parent or other proxy respondent for the child. The current study included only children younger than 6 years. We estimated the proportion of children ever breastfed from the question, “Was ______ ever breastfed or fed breastmilk?”; the proportion exclusively breastfed at a given age from “How old was ______ when ______ was first fed something other than breastmilk or water, including formula, juice, or solid foods?”; and the proportion still breastfed at a given age from “How old was ______ when ______ completely stopped breastfeeding or being fed breastmilk?”
The sociodemographic and environmental factors that we considered in this analysis were those identified in previous studies as important predictors of breastfeeding behaviors.10,11 NHANES III classified the race and ethnicity of respondents as non-Hispanic White, non-Hispanic Black, Mexican American, or other. The survey defined maternal age as that of the mother at the baby's birth. Education of household head was represented by the highest grade the family reference person completed. Smoking status referred to whether the mother smoked during pregnancy. We used selfreported maternal height and weight at the time of the household interview to calculate body mass index (BMI; weight in kg/height in m2), which was categorized as normal weight (BMI < 25), overweight (BMI = 25.0–29.9), and obese (BMI ≥ 30).12
NHANES III did not collect data on gestational age, maternal education, or parity, but we obtained this information from data linkages with the children's birth certificates. We defined prematurity as a gestational age of less than 37 weeks. Maternal education was classified the same way as for household-head education, and parity was classified as primiparous (i.e., the mother had had no previous live births) or multiparous.
The entire 6-year NHANES III sampled a total of 8765 children younger than 6 years. The overall interview response rate for these children was approximately 94%. Data on ever breastfeeding, exclusive breastfeeding, and breastfeeding duration were available for approximately 99% of the interviewed children. We calculated the weighted percentages and their standard errors with SUDAAN to take into account the complex sample design.13
RESULTS
The proportions of children exclusively breastfed were approximately 47% at 7 days after birth, 32% at 2 months, 19% at 4 months, and 10% at 6 months, whereas the proportions of children still being breastfed at these ages were approximately 52%, 40%, 29%, and 22%, respectively. Table 1 ▶ shows that at each of these time points, exclusive breastfeeding was least common among low-birthweight, premature, or non-Hispanic Black infants and those of mothers who were younger than 20 years, had lower education or income, smoked during pregnancy, or lived in the South.
TABLE 1.
—Proportion of Children Exclusively Breastfed (BF), by Sociodemographic and Environmental Factors: NHANES III (Phase II, 1991–1994)
| Exclusively BF at 7 Days | Exclusively BF at 2 mo | Exclusively BF at 4 mo | Exclusively BF at 6 mo | |||||
| Characteristic | n | Weighted % (SE) | n | Weighted % (SE) | n | Weighted % (SE) | n | Weighted % (SE) |
| All infants | 3836 | 47.4 (2.7) | 3836 | 32.2 (2.4) | 3651 | 19.4 (1.4) | 3463 | 9.5 (1.3) |
| Male infants | 1928 | 48.8 (3.5) | 1928 | 32.8 (3.4) | 1836 | 19.2 (1.6) | 1732 | 9.3 (1.3) |
| Female infants | 1908 | 46.0 (2.4) | 1908 | 31.6 (2.0) | 1815 | 19.7 (1.7) | 1731 | 9.6 (1.8) |
| Birthweight | ||||||||
| < 2500 g | 324 | 25.8 (3.7) | 324 | 17.5 (3.9) | 307 | 13.2 (3.9) | 297 | 7.3 (3.8) |
| Normal | 3498 | 49.4 (2.9) | 3498 | 33.5 (2.6) | 3330 | 20.0 (1.5) | 3152 | 9.7 (1.4) |
| Maturity | ||||||||
| Premature | 304 | 28.4 (5.1) | 304 | 14.7 (3.2) | 291 | 5.2 (1.7) | 282 | 2.7 (1.4) |
| Full term | 2475 | 47.4 (3.3) | 2475 | 31.9 (3.0) | 2349 | 19.9 (1.8) | 2221 | 9.6 (1.8) |
| Child race/ethnicity | ||||||||
| Non-Hispanic White | 1398 | 55.0 (3.3) | 1398 | 36.2 (3.2) | 1290 | 22.3 (1.8) | 1178 | 10.9 (1.7) |
| Non-Hispanic Black | 1047 | 22.8 (2.1) | 1047 | 16.2 (1.7) | 1020 | 8.6 (1.5) | 993 | 4.2 (0.9) |
| Mexican American | 1112 | 47.7 (2.5) | 1112 | 36.4 (2.1) | 1081 | 21.4 (1.4) | 1055 | 7.1 (0.9) |
| Other | 279 | 42.6 (5.6) | 279 | 30.5 (5.8) | 260 | 18.2 (4.9) | 237 | 11.5 (4.2) |
| Maternal age, y | ||||||||
| < 20 | 577 | 28.6 (3.4) | 577 | 21.0 (3.0) | 553 | 9.4 (2.3) | 535 | 4.1 (1.4) |
| 20–24 | 1105 | 37.5 (2.6) | 1105 | 25.1 (2.7) | 1059 | 12.6 (1.6) | 993 | 5.1 (1.3) |
| 25–29 | 1118 | 52.0 (2.7) | 1118 | 32.6 (2.6) | 1058 | 18.9 (1.5) | 1009 | 8.1 (1.3) |
| ≥ 30 | 1026 | 58.4 (4.1) | 1026 | 42.0 (3.7) | 971 | 29.3 (2.6) | 916 | 16.3 (2.5) |
| Maternal education | ||||||||
| Less than high school | 887 | 29.5 (3.6) | 887 | 21.9 (3.2) | 844 | 11.8 (2.9) | 815 | 5.7 (2.6) |
| High school | 1111 | 38.1 (2.6) | 1111 | 24.9 (2.5) | 1048 | 12.9 (1.7) | 982 | 4.5 (0.6) |
| Some college | 543 | 55.5 (4.1) | 543 | 34.2 (4.2) | 510 | 24.5 (3.4) | 473 | 12.4 (2.9) |
| College graduate | 157 | 72.6 (5.8) | 157 | 53.6 (7.7) | 147 | 38.0 (5.1) | 132 | 19.5 (6.6) |
| Household head education | ||||||||
| Less than high school | 1296 | 29.8 (3.4) | 1296 | 24.5 (3.6) | 1256 | 13.6 (2.8) | 1212 | 7.1 (2.8) |
| High school | 1302 | 39.2 (3.0) | 1302 | 24.2 (2.5) | 1228 | 11.6 (1.8) | 1158 | 5.4 (1.5) |
| Some college | 613 | 56.0 (2.3) | 613 | 37.1 (2.7) | 574 | 27.6 (2.7) | 538 | 16.3 (3.1) |
| College graduate | 578 | 73.2 (4.1) | 578 | 49.9 (4.6) | 547 | 31.8 (2.8) | 512 | 13.1 (2.7) |
| Parity | ||||||||
| Primiparous | 1359 | 47.0 (2.9) | 1359 | 29.7 (2.5) | 1296 | 17.8 (1.9) | 1223 | 7.3 (1.2) |
| Multiparous | 2008 | 47.5 (3.5) | 2008 | 33.4 (3.1) | 1907 | 20.1 (1.8) | 1816 | 10.0 (1.9) |
| Smoking in pregnancy | ||||||||
| Yes | 681 | 32.8 (3.3) | 681 | 17.4 (3.1) | 646 | 8.1 (1.8) | 611 | 3.3 (1.3) |
| No | 3141 | 51.7 (2.7) | 3141 | 36.4 (2.7) | 2991 | 22.6 (1.7) | 2838 | 11.2 (1.5) |
| Mother's BMI | ||||||||
| Normal (< 25) | 2095 | 52.5 (2.7) | 2095 | 35.4 (2.5) | 1989 | 21.0 (1.5) | 1874 | 9.4 (1.1) |
| Overweight (25–29) | 881 | 39.5 (3.6) | 881 | 28.2 (3.7) | 827 | 18.3 (3.1) | 783 | 10.6 (2.7) |
| Obese (≥ 30) | 662 | 38.7 (5.0) | 662 | 25.9 (4.3) | 640 | 15.1 (2.8) | 617 | 9.2 (3.4) |
| Residence | ||||||||
| Metropolitan | 2108 | 50.3 (3.2) | 2108 | 35.1 (3.2) | 2018 | 19.8 (1.7) | 1912 | 8.7 (1.4) |
| Rural | 1728 | 44.1 (4.5) | 1728 | 28.9 (3.7) | 1633 | 18.9 (2.1) | 1551 | 10.3 (2.1) |
| Region | ||||||||
| Northeast | 516 | 42.4 (4.1) | 516 | 25.5 (3.4) | 485 | 17.1 (2.7) | 453 | 11.7 (3.2) |
| Midwest | 713 | 48.5 (3.3) | 713 | 33.4 (3.2) | 664 | 22.8 (2.2) | 633 | 9.4 (0.9) |
| South | 1775 | 37.9 (4.3) | 1775 | 23.3 (2.9) | 1703 | 12.1 (2.0) | 1615 | 4.4 (0.6) |
| West | 832 | 64.9 (4.3) | 832 | 50.0 (3.8) | 799 | 29.2 (1.7) | 762 | 15.5 (2.5) |
| Poverty–income ratio | ||||||||
| 0–99% | 1378 | 32.2 (4.0) | 1378 | 23.2 (3.5) | 1329 | 13.2 (2.7) | 1290 | 6.8 (2.4) |
| 100–184% | 822 | 42.5 (3.2) | 822 | 29.1 (2.8) | 781 | 17.0 (2.0) | 731 | 10.4 (1.6) |
| 185–349% | 844 | 52.9 (3.4) | 844 | 39.9 (3.6) | 790 | 24.0 (2.4) | 746 | 9.8 (1.5) |
| >350% | 523 | 66.2 (3.8) | 523 | 37.3 (3.1) | 496 | 23.9 (3.2) | 460 | 10.9 (3.2) |
| Missing values | 269 | 37.5 (6.6) | 269 | 29.2 (6.0) | 255 | 17.4 (4.4) | 236 | 11.9 (3.8) |
Notes. (SE) = standard error. Missing numbers for each factor can be derived from the difference between the total number of infants and the summary number for each factor (see the example given under “Poverty–Income Ratio”).
The proportions of children ever breastfed and still being breastfed at 6 and 12 months were also stratified by sociodemographic and environmental factors (Table 2 ▶). We observed patterns similar to those for the exclusively breastfed children. In addition, we found lower breastfeeding initiation and duration among mothers who were overweight or obese and among families living in rural areas. Although primiparous mothers had a higher rate of initiating breastfeeding than did multiparous mothers, they had a lower rate of continuing breastfeeding throughout the infant's first year.
TABLE 2.
—Ever Breastfed and Breastfeeding Duration, by Sociodemographic and Environmental Factors: NHANES III (Phases I and II, 1988–1994)
| Ever Breastfed | Breastfeeding at 6 mo | Breastfeeding at 12 mo | ||||
| Characteristic | n | Weighted % (SE) | n | Weighted % (SE) | n | Weighted % (SE) |
| All infants | 8215 | 53.6 (1.7) | 7363 | 22.4 (1.2) | 6123 | 8.9 (0.8) |
| Male infants | 4062 | 53.7 (2.1) | 3636 | 23.0 (1.7) | 3009 | 9.2 (1.2) |
| Female infants | 4153 | 53.6 (1.7) | 3727 | 21.9 (1.2) | 3114 | 8.5 (0.8) |
| Birthweight | ||||||
| < 2500 g | 669 | 34.1 (3.0) | 617 | 11.8 (2.2) | 533 | 3.9 (1.5) |
| Normal | 7350 | 55.5 (1.8) | 6557 | 23.5 (1.3) | 5417 | 9.3 (0.9) |
| Maturity | ||||||
| Premature | 709 | 35.7 (4.3) | 650 | 11.1 (2.3) | 554 | 6.5 (2.0) |
| Full term | 5597 | 54.2 (1.8) | 4997 | 23.4 (1.6) | 4158 | 9.0 (1.0) |
| Child race/ethnicity | ||||||
| Non-Hispanic White | 3067 | 60.2 (2.0) | 2580 | 26.6 (1.6) | 1863 | 10.6 (1.3) |
| Non-Hispanic Black | 2172 | 26.3 (1.5) | 2033 | 8.3 (0.8) | 1842 | 2.7 (0.6) |
| Mexican American | 2479 | 56.0 (2.0) | 2325 | 22.5 (1.4) | 2112 | 9.9 (0.8) |
| Others | 497 | 53.6 (3.5) | 425 | 19.0 (2.8) | 306 | 6.5 (1.8) |
| Maternal age, y | ||||||
| < 20 | 1265 | 32.5 (2.7) | 1155 | 9.5 (1.7) | 981 | 4.0 (1.0) |
| 20–24 | 2321 | 44.8 (1.9) | 2084 | 13.4 (1.4) | 1737 | 4.4 (0.9) |
| 25–29 | 2494 | 58.5 (1.9) | 2236 | 24.8 (1.7) | 1877 | 9.8 (1.4) |
| ≥ 30 | 2104 | 65.3 (2.3) | 1857 | 33.3 (2.0) | 1497 | 13.7 (1.4) |
| Maternal education | ||||||
| Less than high school | 1584 | 30.3 (2.1) | 1426 | 10.0 (1.7) | 1187 | 3.9 (1.1) |
| High school | 2201 | 45.4 (2.3) | 1941 | 16.0 (1.2) | 1522 | 5.7 (1.2) |
| Some college | 994 | 62.1 (2.6) | 865 | 26.3 (2.8) | 661 | 8.2 (1.9) |
| College graduate | 283 | 81.8 (3.4) | 233 | 43.6 (5.8) | 159 | 20.7 (5.4) |
| Household head education | ||||||
| Less than high school | 2839 | 35.8 (2.1) | 2616 | 14.9 (1.9) | 2276 | 7.2 (1.3) |
| High school | 2690 | 46.0 (2.1) | 2391 | 15.9 (1.1) | 1955 | 6.5 (1.2) |
| Some college | 1349 | 60.1 (1.9) | 1182 | 24.9 (1.9) | 979 | 10.0 (1.6) |
| College graduate | 1149 | 80.2 (2.2) | 1002 | 39.1 (2.4) | 770 | 13.5 (2.0) |
| Parity | ||||||
| Primiparous | 2895 | 55.2 (1.7) | 2582 | 19.1 (1.4) | 2096 | 6.0 (0.8) |
| Multiparous | 4355 | 52.2 (2.0) | 3903 | 24.6 (1.6) | 3246 | 10.2 (1.2) |
| Smoking in pregnancy | ||||||
| Yes | 1632 | 35.9 (2.1) | 1452 | 9.4 (1.0) | 1161 | 4.4 (1.0) |
| No | 6551 | 59.1 (1.7) | 5884 | 26.4 (1.4) | 4937 | 10.2 (1.0) |
| Mother's BMI | ||||||
| Normal (< 25) | 4617 | 58.1 (1.7) | 4107 | 25.0 (1.3) | 3345 | 10.0 (1.0) |
| Overweight (25–29) | 1833 | 46.4 (2.4) | 1621 | 17.3 (1.7) | 1361 | 5.7 (0.9) |
| Obese (≥ 30) | 1262 | 44.8 (3.6) | 1166 | 16.9 (2.8) | 1011 | 5.6 (1.8) |
| Residence | ||||||
| Metropolitan | 4370 | 58.8 (2.2) | 3920 | 24.1 (1.8) | 3290 | 9.8 (1.2) |
| Rural | 3845 | 48.5 (2.9) | 3443 | 20.8 (2.0) | 2833 | 7.9 (1.2) |
| Region | ||||||
| Northeast | 1058 | 47.6 (3.5) | 906 | 18.2 (2.4) | 703 | 8.2 (1.4) |
| Midwest | 1575 | 56.2 (2.1) | 1398 | 24.8 (1.6) | 1081 | 9.3 (2.0) |
| South | 3360 | 44.1 (1.8) | 3024 | 16.0 (1.7) | 2588 | 5.4 (1.2) |
| West | 2222 | 69.8 (3.6) | 2035 | 32.7 (2.5) | 1751 | 14.0 (1.6) |
| Poverty–income ratio | ||||||
| 0–99% | 2857 | 36.5 (2.6) | 2636 | 14.3 (1.7) | 2286 | 7.6 (1.1) |
| 100–184% | 1758 | 50.1 (1.9) | 1572 | 20.3 (1.5) | 1307 | 6.5 (1.2) |
| 185–349% | 1847 | 58.5 (1.9) | 1625 | 27.3 (1.9) | 1302 | 11.9 (1.8) |
| > 350% | 994 | 75.4 (2.2) | 854 | 30.7 (2.7) | 657 | 9.2 (2.0) |
| Missing value | 759 | 45.8 (3.6) | 676 | 14.9 (1.9) | 571 | 6.4 (1.6) |
Notes. (SE) = standard error. Missing numbers for each factor can be derived from the difference between the total number of infants and the summary number for each factor (see the example given under “Poverty–Income Ratio”).
DISCUSSION
Less than half of the children in NHANES III began exclusive breastfeeding. At age 2 months, the percentage of infants still being exclusively breastfed was considerably lower than the percentage who were receiving any breast milk at this point. By the age of 6 months, slightly less than 10% of infants were being exclusively breastfed.
Although the factors that influence the initiation and duration of breastfeeding have been broadly studied,10,11 previous studies have rarely examined the factors associated with exclusive breastfeeding. Our study indicates that the proportion of infants exclusively breastfed varied by subgroup, with the lowest rate found among non-Hispanic Black and premature infants and the highest rate among infants of mothers who had graduated from college. Our study also suggests that the factors associated with exclusive breastfeeding were similar to those associated with the initiation and duration of any breastfeeding.10,11
Our results regarding the initiation and duration of breastfeeding are similar to those from previous Ross Laboratories Mothers' Surveys.14 Our analysis showed that only 3 subgroups in NHANES III met the Healthy People 2010 goal15 of 75% for breastfeeding initiation: mothers who had graduated from college (81.8%), families with a household head who had graduated from college (80.2%), and families with an income exceeding 350% of the poverty–income ratio (75.4%). None of the subgroups met the goals for breastfeeding at 6 months (50%) or 12 months (25%).
In summary, this is the first nationally representative study available that indicates that initiation and maintenance of exclusive breastfeeding are low in the United States. Public health efforts are needed to improve the rate of exclusive breastfeeding—and, in particular, the duration of such feeding—among non-Hispanic Blacks and socioeconomically disadvantaged groups.
R. Li planned the study, analyzed the data, and wrote the brief. C. Gillespie extracted the data set and conducted preliminary analysis for this study. C. Ogden linked the NHANES III with children's birth certificates and analyzed data for gestational age, maternal education, and parity. C. Ballew and L. Grummer-Strawn assisted with study design, supervised data analysis, and contributed to the writing of the brief.
Peer Reviewed
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