Comparison of gestational weight gain-related pregnancy outcomes in American primiparous and multiparous women.

Background: In Danish data, the tradeoffs between mother and infant in the risks of adverse pregnancy outcomes were reached at lower gestational weight gain (GWG) among multiparous than among primiparous women. It is unknown whether the same difference exists among American women.

Objective: The objective was to determine whether these tradeoffs also differ by parity among women in a contemporary American birth cohort.

Design: Data from 822 primiparous and 2055 multiparous American women who participated in the Infant Feeding Practices Study II (2005-2007), a national cohort study, were analyzed. Their self-reported GWG was divided into 4 categories (≤10, >10 to <15, 15 to <20, and ≥20 kg). GWG-specific absolute adjusted risks for emergency cesarean delivery, birth of a small-for-gestational-age (SGA) or large-for-gestational-age (LGA) infant, and postpartum weight retention at 6 mo were estimated by multiple logistic regression analyses for women in 3 categories of prepregnancy body mass index.

Results: Primiparous women gained more weight during pregnancy than did multiparous women (mean ± SD: 15.9 ± 6.9 compared with 13.5 ± 6.2 kg; P < 0.0001). The absolute adjusted risk of postpartum weight retention rose steeply with increasing GWG among both primiparous and multiparous women. The risk of emergency cesarean delivery and of delivering LGA infants increased with increasing GWG only among multiparous women. The risk of SGA tended to decrease with increasing GWG in both parity groups.

Conclusion: These findings extend the concept of a lower optimal GWG among multiparous than primiparous women to American women.