Maternal body mass index and risk of neonatal adverse outcomes in China: a systematic review and meta-analysis

Background: Maternal body mass index is linked to short- and long-term unfavorable health outcomes both for child and mother. We conducted a systematic review and meta-analysis of population-based cohort studies to evaluate maternal BMI and the risk of harmful neonatal outcomes in China. Methods: Six databases identified 2454 articles; 46 met the inclusion criteria for this study. The dichotomous data on maternal BMI and harmful neonatal outcomes were extracted. Pooled statistics (odds ratios, ORs) were derived from Stata/SE, ver. 12.0. Sensitivity analyses assessed the robustness of the results. Meta-regression and subgroup meta-analyses explored heterogeneity. Results: The meta-analysis revealed that compared with normal BMI, high maternal BMI is associated with fetal overgrowth, defined as macrosomia >= 4000g (OR 1.91, 95% CI 1.75-2.09); birth weight 90% for gestational age (OR 1.88, 95% CI 1.64-2.15); and increased risk of premature birth (OR 1.38, 95% CI 1.25-2.52) and neonatal asphyxia (OR 1.74, 95% CI 1.39-2.17). Maternal underweight increased the risk of low birth weight (OR 1.61, 95% CI 1.33-1.93) and small for gestational age (OR 1.75, 95% CI 1.51-2.02). Conclusions: Raised as well as low pre-pregnancy BMI is associated with adverse neonatal outcomes. Management of weight during pregnancy might help reduce their adverse neonatal outcomes in future intervention studies or programmes.