Abstract
BACKGROUND: The relationship between maternal body composition and offspring birth weight remains controversial, and limited research exists in patients with gestational diabetes mellitus (GDM). This study therefore aimed to explore this association in GDM. METHODS: Pregnant women diagnosed with GDM were enrolled and followed until delivery. Maternal body composition was assessed via bioelectrical impedance analysis (BIA) at a mean gestational age of 26.3 weeks. Multiple regression was used to analyze associations between maternal body composition and offspring birth weight; restricted cubic spline (RCS) models were employed to examine nonlinear relationships, and two-piecewise logistic regression was applied to quantify threshold effects. RESULTS: This cohort study involved 929 pregnant women with GDM, among whom 112 delivered newborns with large-for-gestational-age (LGA). After covariate adjustment, offspring birth weight was positively correlated with maternal total body water (TBW), intracellular fluid (ICF), extracellular fluid (ECF), fat mass (FM), fat-free mass (FFM), muscle mass (MM), protein, percent protein, minerals, and percent minerals in mothers with GDM. Multiple logistic regression indicated that several of these body composition parameters were associated with increased risk of LGA. The RCS model revealed threshold‑type nonlinear associations between LGA risk and maternal TBW, ICF, ECF, FFM, MM, protein, and minerals, while no significant nonlinear association was observed for maternal FM, it increases below inflection points but plateaus thereafter. CONCLUSIONS: The body composition indicators of GDM pregnant women are positively correlated with the neonatal birth weight. However, except for FM, other indicators show a non-linear correlation with the risk of LGA. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40200-026-01902-x.