Impact of Parity and Breastfeeding on Racial Differences in Obesity

In 1949, Sheldon first described maternal obesity as the development of obesity and other long-lasting health consequences of having a baby,¹ and studies have confirmed the association of number of children and obesity many years after childbirth.² Factors influencing postpartum weight retention include being overweight or obese pregravid, excessive gestational weight gain, higher parity, and not breastfeeding.³ Although black women appear to be twice as likely as white women to retain weight 5 years postpartum,⁴ the majority of studies examining long-term postpartum weight retention have not been able to examine racial differences because cohorts of older women were predominantly white.

In the current issue of Journal of Women's Health, Cohen et al.⁵ used a cross-sectional design to assess the association of parity, breastfeeding, and obesity. The objective of this study was to determine if obesity in later life was associated with parity or breastfeeding and if these associations differed between black and white women with similar incomes. Participants in this cohort were aged 40–79 at enrollment and attended 1 of 48 Comprehensive Health Centers (CHC) in 12 southeastern U.S. states. At all levels of parity and breastfeeding, black women had higher body mass index (BMI) and had gained more weight since age 21 than white women. Having five or more children compared with nulliparity was associated with a 37% increase in risk of obesity in later life among white women and a 22% increase in risk of obesity in black women. Cumulative breastfeeding ≥12 months was associated with a 32% reduction in risk of obesity in white women and had no effect on obesity risk in black women. Among women with at least one live birth, black women were more likely than white women to have never breastfed (69% vs. 64%).

The limitations of this cross-sectional study include the use of self-reported weight and height at the time of enrollment and asking women to recall their weight at age 21. Women were also asked to recall the total number of months (counting all pregnancies) that they breastfed. The validity of maternal recall of breastfeeding has been studied, although predominantly in white women.⁶ The major strengths of this large cohort (n = 31,184) are that all women were of a similarly low income level (60% with annual household income <$15,000), 74% were black, and there was a wide range of parity (17% had five or more children) and weight levels (55% had BMI ≥30).

Although the associations with obesity and parity in the study by Cohen et al.⁵ for both white and black women are modest, they still have public health importance. Understanding risk factors associated with obesity in targeted groups provides an opportunity for changing the obesity trajectory. Results also suggest a potential role for breastfeeding in reducing the risk of obesity in later life for white women. Recent studies have shown a possible beneficial effect of breastfeeding on the risk of metabolic syndrome⁷ and cardiovascular disease (CVD).^8,9 Breastfeeding, especially in black women, may be confounded because overweight and obese women are less likely to breastfeed.¹⁰ Prospective studies are needed to fully understand the impact of breastfeeding on risk for obesity in black women.

Potential interventions to target obesity associated with parity include pregravid weight loss, gestational weight restrictions, and postpartum weight loss interventions that promote breastfeeding, diet, and exercise. Formal interventions that offer opportunities to engage in behaviors that build skills related to weight loss diets and physical activity could be very attractive to reproductive-aged women who would not otherwise consider similar programs.

Pregnant women are an important high-risk population for obesity in later life. Public health interventions should target women contemplating pregnancy. In addition to recommending folic acid supplementation, these women should be encouraged to develop regular exercise programs that are sustainable during and after pregnancy. Their partner should also be encouraged to start an obesity prevention program, as studies have found a similar pattern of weight gain in fathers.^11,12

Prenatal visits could include classes on nutrition, exercise, and lifestyle changes associated with having small children in the home. In addition to advice about how much weight to gain during pregnancy, women should be informed about the potential long-term health benefits of breastfeeding. Specific counseling for postpartum diet and exercise programs should be strongly recommended during the first pregnancy, with reinforcement during subsequent pregnancies.

More needs to be done to motivate overweight and obese women to lose weight after having their first child. Understanding which women are highly motivated to change their behaviors, not just interested in losing weight, allows for studies and clinical programs to target this group. Postpartum weight loss interventions have had difficulty engaging even highly motivated women to attend diet and exercise classes.^13,14 Retention in weight loss interventions may be improved for black women by using existing social support groups, such as family and church members, and by using culturally appropriate lay navigators.¹⁵

Given the known racial differences in the prevalence of obesity, a better understanding of the role that pregnancy plays in black women's risk for obesity will help target weight loss interventions. Dietary restrictions and exercise are needed, but these are huge behavior modifications requiring resources, support, and motivation to sustain. Reproductive-aged women need to be better informed and prepared for the significant weight gains associated with having children.

Acknowledgments

This work is supported by grants from NIH/NIDDK (DK64986 and DK75439).

Disclosure Statement

No competing financial interests exist.