By Rebecca H. Allen, MD, MPH
Assistant Professor, Department of Obstetrics and Gynecology, Warren Alpert Medical School of Brown University, Women and Infants Hospital, Providence, RI
Synopsis: In this prospective cohort study, being overweight or obese pre-pregnancy and excessive weight gain during pregnancy were associated with postpartum weight retention (> 20 pounds) at 1 year. Protective factors were breastfeeding at 6 months and moderate exercise.
Source: Endres LK, et al. Postpartum weight retention risk factors and relationship to obesity at 1 year. Obstet Gynecol 2015;125:144-152.
This is a nested prospective cohort study of 774 women who were participants in the multi-site Community Child Health Network of the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Sites of recruitment included Baltimore, Los Angeles, Washington, DC, Lake County, Illinois, and eastern North Carolina. The main study enrolled women ages 18-40 years with a live birth at 20 weeks’ gestation or longer. Women who could not or were unlikely to become pregnant again in the future were excluded (those who underwent postpartum sterilization or had four or more children). This sub-study included those women who had pre-pregnancy height and weight data available and weight data at 1 year postpartum without a subsequent pregnancy in that year. Body mass index (BMI) was calculated and used standard Institute of Medicine (IOM) definitions (underweight < 18.5 kg/m2, normal weight 18.5-24.9 kg/m2, overweight 25.0-29.9 kg/m2, and obese 30.0 kg/m2 or higher). There was no difference between the women eligible for the sub-study and the 1736 women who were excluded in terms of age, race, parity, or income level. Other data collected included insurance, education, exercise, breastfeeding, smoking, and sleep.
The mean age of the study population was 26 (± 5.8) years and one-third of the women were enrolled after having their first child. Approximately, one-half of the sample reported African American race, one-quarter Hispanic, and one-quarter white. Pre-pregnancy, 4% of the women were underweight, 40% normal weight, 26% overweight, and 30% obese. At 1 year postpartum, among women who were normal weight before pregnancy, 30% became overweight and 2% obese. Among women who were overweight pre-pregnancy, 44% became obese by 1 year postpartum. In fact, 75% of the women were heavier at 1 year postpartum than pre-pregnancy. Half of the sample gained more than the recommended amount of weight gain during pregnancy per IOM guidelines. In multivariate analysis, excessive weight gain during pregnancy (odds ratio [OR], 1.08; 95% confidence interval [CI], 1.06-1.10) and pre-pregnancy BMI (overweight OR, 3.25; 95% CI, 1.90-5.55; obese OR, 3.72; 95% CI 2.17-6.38) increased the odds of excessive weight retention (> 20 lbs or more) at 1 year postpartum while breastfeeding at 6 months (OR, 0.46; 95% CI, 0.24-0.87) and moderate exercise (OR, 0.61; 95% CI, 0.40-0.93) was protective.
COMMENTARY
More than one-third (78.6 million) of adults in the United States are obese,1 a major public health problem. Pregnancy and its accompanying “baby weight” have long been suspected to be a risk factor for future weight gain and obesity. Obesity puts women at risk for pregnancy complications as well as for their lifelong health in terms of cardiovascular disease, diabetes, and osteoarthritis.2 During pregnancy, health care providers should counsel women on the IOM guidelines for weight gain, which are categorized by pre-pregnancy BMI.3 For singleton pregnancies, these guidelines state that underweight women should gain no more than 28-40 lbs, normal weight women 25-35 lbs, overweight women 15-25 lbs, and obese women 11-20 lbs, respectively, during pregnancy. Some trials have shown success in limiting gestational weight gain with combining physical activity and diet counseling during pregnancy. One meta-analysis indicated that this approach reduced gestational weight gain by 1.2 kg (2.6 lbs), where the mean gestational weight gain was 13 kg (28 lbs).4
The authors of this study confirm that pre-pregnancy BMI and excessive weight gain during pregnancy are risk factors for postpartum weight retention at 1 year. Women who do not return to their pre-pregnancy weight postpartum are at risk of becoming more overweight with every pregnancy in their lifetime. While the source of the study population was mostly low-income, by design, it was racially diverse and the results are likely generalizable. Some limitations of the study include breastfeeding assessment, which could not distinguish between partial and exclusive breastfeeding, and the fact that physical activity was self-reported. Nevertheless, the variables that remained predictive in multivariable analysis make biologic sense.
The American College of Obstetricians and Gynecologists recommends the following for overweight or obese women considering pregnancy or who are pregnant.5
- Preconception assessment and counseling are strongly encouraged and should include the provision of specific information concerning the maternal and fetal risks of obesity in pregnancy and encouragement to undertake a weight-reduction program.
- At the initial prenatal visit, height and weight should be recorded for all women to allow calculation of BMI, and recommendations for appropriate weight gain, guided by IOM recommendations, should be reviewed both at the initial visit and periodically throughout pregnancy.
- Nutrition consultation should be offered to all overweight or obese women, and they should be encouraged to follow an exercise program. Nutrition and exercise counseling should continue postpartum and before attempting another pregnancy.
While these recommendations may be difficult to incorporate into a busy practice, women could be referred to a nutritionist and/or weight loss program. At the very least, women deserve to hear the recommended guidelines for weight gain in pregnancy and weight should be monitored at each prenatal visit. There is even research suggesting that obese women may not need to gain any weight in pregnancy at all.6 This is an area that is changing rapidly and it may be that the IOM changes its recommendations in the future.
References
- Centers for Disease Control and Prevention. Adult Obesity Facts. Available at http://www.cdc.gov/obesity/data/adult.html. Accessed Jan. 2, 2015.
- Chescheir NC. Global obesity and the effect on women’s health. Obstet Gynecol 2011;117:1213-1222.
- Institute of Medicine. Weight Gain During Pregnancy: Reexamining the Guidelines. Washington DC. National Academies Press. 2009.
- Streuling I, et al. Can gestational weight gain be modified by increasing physical activity and diet counseling? A meta-analysis of interventional trials. Am J Clin Nutr 2010;92:678-687.
- ACOG Committee Opinion No. 549. Obesity in Pregnancy. January, 2013.
- Kominiarek MA, et al. Gestational weight gain and obesity: Is 20 pounds too much? Am J Obstet Gynecol 2013;209:214.e1-11.