Meta-analysis Links Abnormal Gestational Weight Gain to Adverse Outcomes in 866,593 Pregnancies

Abnormal gestational weight gain (GWG) has been associated with a wide range of adverse maternal and neonatal outcomes; however, existing evidence remains inconsistent, particularly across different regions and levels of national development. Moreover, the applicability of commonly used GWG guidelines in diverse populations, especially in developing countries, remains unclear. This systematic review and meta-analysis aimed to comprehensively evaluate the association between abnormal GWG and adverse pregnancy outcomes using multinational cohort data. We conducted a systematic review and meta-analysis of cohort studies published from 2009 to April 2025. Studies defining GWG by IOM/WHO/ACOG guidelines and reporting outcomes like cesarean section, preterm birth, preeclampsia, macrosomia, or LGA/SGA were included. Data extraction and quality assessment (via NOS) were performed independently by reviewers. Pooled ORs with 95% CIs were calculated using fixed/random-effects models in Stata. Seventeen studies involving 866,593 pregnant women were included. Compared with adequate GWG, excessive GWG was associated with significantly increased risks of cesarean section (OR = 1.32, 95% CI: 1.23–1.42), preeclampsia (OR = 2.05, 95% CI: 1.67–2.52), macrosomia (OR = 2.18, 95% CI: 2.03–2.35), and LGA (OR = 2.20, 95% CI: 1.97–2.46), while no significant association was observed with preterm birth or SGA. In contrast, inadequate GWG was associated with an increased risk of preterm birth (OR = 1.45, 95% CI: 1.08–1.94) but lower risks of cesarean section (OR = 0.89, 95% CI: 0.82–0.98), macrosomia (OR = 0.70, 95% CI: 0.55–0.91), and LGA (OR = 0.65, 95% CI: 0.56–0.75). Substantial regional and developmental differences were observed, with stronger associations generally found in developing countries. Our findings highlight that the effects of abnormal GWG are highly context-dependent, varying substantially by region, national development level, and guideline standards. These results underscore the need for population-specific GWG recommendations and targeted gestational weight management strategies, particularly in developing countries.