Abstract
PURPOSE: We aimed to assess the association between postpartum weight retention (PPWR) in the 4th-week post-delivery and the risk of large-for-gestational-age (LGA) infants in the second pregnancy. METHODS: This nationwide prospective birth cohort analysis included 3137 women who delivered their first two live singletons between 2011 and 2014. The PPWR was defined as the body mass index (BMI) after 4 weeks of the first birth minus the pre-pregnancy BMI of the first pregnancy. LGA infants were compared among four PPWR groups: less than - 1 (a BMI loss of > 1 unit), - 1 to < 1 (the reference: stable PPWR group), 1 to < 3 (a BMI gain of 1-3 unit) and ≥ 3 (a BMI gain of > 3 unit). PPWR was assessed not only in all women but also in women with a BMI < 25 and ≥ 25 kg/m(2), and adjusted odds ratios (ORs) were calculated for LGA infants by multiple logistic regression. RESULTS: The incidence of LGA infants was 8.8% (277 out of 3137). After adjusting for potential confounding factors, no association was observed between the risk of an LGA infant in the second pregnancy and the PPWR in all eligible women. Similarly, no association was observed between LGA risk in the second pregnancy and thePPWR in the pre-pregnancy BMI < 25 kg/m(2) (normal) and ≥ 25 kg/m(2) (overweight/obese) groups. CONCLUSION: PPWR measured in the 4th-week post-delivery was not associated with an increased risk of LGA infants in the second pregnancy. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40200-025-01749-8.