Factors Affecting BMI Changes in Mothers during the First Year Postpartum

Alissa D Smethers; Jillian C Trabulsi; Virginia A Stallings; Mia A Papas; Julie A Mennella

doi:10.3390/nu15061364

Factors Affecting BMI Changes in Mothers during the First Year Postpartum

Nutrients. 2023 Mar 11;15(6):1364. doi: 10.3390/nu15061364.

Authors

Alissa D Smethers¹, Jillian C Trabulsi², Virginia A Stallings³, Mia A Papas⁴, Julie A Mennella¹

Affiliations

¹ Monell Chemical Senses Center, Philadelphia, PA 19104, USA.
² Department of Behavioral Health and Nutrition, University of Delaware, Newark, DE 19173, USA.
³ Children's Hospital of Philadelphia and Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
⁴ Institute for Research on Equity and Community Health, ChristianaCare, Wilmington, DE 19801, USA.

Abstract

We tested the hypotheses that mothers of infants who exclusively breastfed would differ in the trajectories of postpartum BMI changes than mothers of infants who exclusively formula fed, but such benefits would differ based on the maternal BMI status prepregnancy (primary hypothesis) and that psychological eating behavior traits would have independent effects on postpartum BMI changes (secondary hypothesis). To these aims, linear mixed-effects models analyzed measured anthropometric data collected monthly from 0.5 month (baseline) to 1 year postpartum from two groups of mothers distinct in infant feeding modality (Lactating vs. Non-lactating). While infant feeding modality group and prepregnancy BMI status had independent effects on postpartum BMI changes, the benefits of lactation on BMI changes differed based on prepregnancy BMI. When compared to lactating women, initial rates of BMI loss were significantly slower in the non-lactating women who were with Prepregnancy Healthy Weight (β = 0.63 percent BMI change, 95% CI: 0.19, 1.06) and with Prepregnancy Overweight (β = 2.10 percent BMI change, 95% CI: 1.16, 3.03); the difference was only a trend for those in the Prepregnancy Obesity group (β = 0.60 percent BMI change, 95% CI: -0.03, 1.23). For those with Prepregnancy Overweight, a greater percentage of non-lactating mothers (47%) gained ≥ 3 BMI units by 1 year postpartum than did lactating mothers (9%; p < 0.04). Psychological eating behavior traits of higher dietary restraint, higher disinhibition, and lower susceptibility to hunger were associated with greater BMI loss. In conclusion, while there are myriad advantages to lactation, including greater initial rates of postpartum weight loss regardless of prepregnancy BMI, mothers who were with overweight prior to the pregnancy experienced substantially greater loss if they breastfed their infants. Individual differences in psychological eating behavior traits hold promise as modifiable targets for postpartum weight management.

Keywords: breast feeding; eating behavior; formula feeding; lactation; postpartum period; prepregnancy body mass index; weight loss.

MeSH terms

Body Mass Index
Breast Feeding
Female
Humans
Infant
Mothers / psychology
Obesity
Overweight*
Postpartum Period*
Pregnancy

Grants and funding

This research was supported by NIH grants R01HD072307, R01HD37119, R03HD94908, and R03HD102303 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development and 1F32 DC018710 from the National Institute of Deafness and Other Communications Disorders. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.