Maternal weight change between 1 and 2 years postpartum: the importance of 1 year weight retention

Abstract

Pregnancy weight gain may lead to long-term increases in maternal BMI for some women. The objective of this study was to examine maternal body weight change 1y-2y postpartum, and to compare classifications of 2y weight retention with and without accounting for 1y-2y weight gain. Early pregnancy body weight (EPW, first trimester) was measured or imputed, and follow-up measures obtained before delivery, 1 year postpartum (1y) and 2 years postpartum (2y) in an observational cohort study of women seeking prenatal care in several counties in upstate New York (n = 413). Baseline height was measured; demographic and behavioral data were obtained from questionnaires and medical records. Associations of 1y-2y weight change (kg) and 1y-2y weight gain (≥2.25 kg) with anthropometric, socioeconomic, and behavioral variables were evaluated using linear and logistic regressions. While mean ± SE 1y-2y weight change was 0.009 ± 4.6 kg, 1y-2y weight gain (≥2.25 kg) was common (n = 108, 26%). Odds of weight gain 1y-2y were higher for overweight (OR(adj) = 2.63, CI(95%) = 1.43-4.82) and obese (OR(adj) = 2.93, CI(95%) = 1.62-5.27) women than for women with BMI <25. Two year weight retention (2y-EPW ≥2.25 kg) was misclassified in 38% (n = 37) of women when 1y-2y weight gain was ignored. One year weight retention (1YWR) (1y-EPW) was negatively related to 1y-2y weight change (β(adj) ± SE = -0.28 ± 0.04, P < 0.001) and weight gain (≥2.25 kg) (OR(adj) = 0.91, CI(95%) = 0.87-0.95). Relations between 1y weight retention and 1y-2y weight change were attenuated for women with higher early pregnancy BMI. Weight change 1y-2y was predicted primarily by an inverse relation with 1y weight retention. The high frequency of weight gain has important implications for classification of postpartum weight retention.

Conflict of interest statement

DISCLOSURE

The authors declared no conflict of interest.

See the online ICMJE Conflict of Interest Forms for this article.

Figures

Figure 1

Subject enrollment. 1y, 1 year postpartum; 2y, 2 years postpartum.

Figure 2

Schematic representation of maternal body weight over time and body weight variable definitions for gestational weight gain, 1y weight retention, 2y weight difference, and late postpartum weight change. 1y, 1 year postpartum; 2y, 2 years postpartum.

Figure 3

Late postpartum weight change (2y–1y weight (kg)) vs. 1y weight retention, by early pregnancy BMI. The relationship was significantly attenuated (P interaction = 0.01) for women who were obese in early pregnancy (βadj ± SE = −0.21 ± 0.10, P = 0.04) as compared with women with BMI <25 (βadj ± SE = −0.33 ± 0.04, P < 0.001). The relationship was not significantly different for women who were overweight in early pregnancy (βadj ± SE = −0.37 ± 0.08, P < 0.001) as compared to women with BMI <25. Adjusted for time between measurements, gestational weight gain, smoking, breastfeeding, education, parity, and income. 1y, 1 year postpartum; 2y, 2 years postpartum.

Figure 4

Adjusted odds ratio (OR) and 95% confidence interval (95% CI) of late postpartum weight gain (2y–1y ≥2.25 kg) associated with a 1 kg increase in one year weight retention (1YWR), by early pregnancy BMI. Interaction terms for overweight (P = 0.01) and obese (P = 0.001) BMI are significantly different from zero. Adjusted for time between measurements, gestational weight gain, smoking, breastfeeding, education, parity, and income. 1y, 1 year postpartum; 2y, 2 years postpartum.