Association of Pregnancy Weight Gain with Infant Birth Weight and Postpartum Weight Retention

Abstract

Purpose: To investigate weight gain during pregnancy and its association with birth weight and weight retention postpartum (PP) among women of different ethnic backgrounds. Methods: Cross-sectional study of 5,863 women participating in the Hawai`i Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) in 1997 and 1998. Postpartum weight and height were measured by WIC staff, weight gain during pregnancy and infant birth weight were self-reported. Ethnicity was also selfreported. The Institute of Medicine guidelines for pregnancy weight gain in relation to levels of prepregnancy body mass index (BMI) were followed. The analysis included bivariate tests of association between prepregnancy BMI, pregnancy weight gain, PP weight retention, infant birth weight and ethnicity. Multivariable analysis was conducted to estimate the independent association of the study variables with PP weight retention, birth weight, and ethnicity. SAS was used to analyze the data. Results: The largest ethnic groups were Hawaiian (29.9%), Caucasian (27.2%), and Filipino (19.8%). Asians, Blacks, Samoans, and Other represented smaller percentages. Thirty percent of women were overweight or obese before pregnancy. There were significant ethnic differences in prepregnancy BMI. Samoans had the highest mean prepregnancy BMI (29.7). Filipinos had the lowest mean prepregnancy BMI (22.5). There were significant differences in pregnancy weight gain. Samoans had the highest mean weight gain (37.3 lbs). Asians had the lowest mean weight gain (29.1bs). Almost one half of women (48.1%) gained more than the IOM recommended pregnancy weight. The average weight retention was 9.4 lbs at five to six months postpartum, and 7.4 lbs after eight months postpartum. There were significant ethnic differences in weight retention with Samoans having the largest average weight retention (17.5 lbs) and Asians the lowest (9.6 lbs). Infant birth weight differed significantly by ethnicity. Birth weight was significantly associated with prepregnancy BMI and pregnancy weight gain. Conclusions: In spite of large racial/ethnic differences, on the average there was almost a two-thirds pound adjusted PP weight retention for each pound of weight gained during pregnancy. Our study suggests a need for integrated women’s health services to include nutritional support during the pre and post conceptual period. Findings of this study will provide guidance in the development of culturally sensitive interventions and counseling.