A prospective study of the effect of childbearing on weight gain in African-American women.

OBJECTIVE: To prospectively assess the influence of bearing a first, second, or later child on weight gain among African-American women in the context of other risk factors. RESEARCH METHODS AND PROCEDURES: Data were obtained in a prospective follow-up study of African-American women from across the U.S. who are participants in the Black Women's Health Study. Postal questionnaires were used to collect baseline data in 1995 and follow-up data in 1997 and 1999. Parous and nulliparous women (11,196) (21 to 39 years old at baseline), of whom 1230 had a singleton birth during follow-up, are the subjects of the present analyses. We assessed change in BMI (kilograms per meter squared) in relation to childbearing during 4 years of follow-up, with use of multivariable linear regression to control for important risk factors.
RESULTS: During 4 years of follow-up, the BMI of participants increased by an average of 1.6 kg/m2, equivalent to a weight gain of approximately 4.4 kg. Women who had a child during follow-up gained more weight than women who remained nulliparous, and those who had a first child gained more than those who had a second or later child. The weight gain associated with childbearing increased with increasing baseline BMI and was appreciable among heavier women. For example, among women with a baseline index of 36, the increase in BMI for women who bore a first child was 1.1 kg/m2 more than that of nulliparous women, equivalent to a difference in weight gain of approximately 3.0 kg. DISCUSSION: Childbearing is an important contributor to weight gain among African-American women.