Interactive effects and relative contribution of prepregnancy overweight and obesity, excessive gestational weight gain and gestational diabetes mellitus to macrosomia: A retrospective cohort in Fujian, China

Aim: To conduct a retrospective cohort study to investigate the association between prepregnancy overweight and obesity, excessive gestational weight gain (GWG), gestational diabetes mellitus (GDM) and macrosomia, both individually and in combination. Methods: Binary logistic regression was used to analyse the effects of overweight and obesity, excessive GWG and GDM on macrosomia, both separately and in combination. The interaction effects between prepregnancy overweight and obesity, excessive GWG and GDM were tested. The population attributable fraction (PAF) was calculated separately when interaction terms were significant. Results: When analysed separately, prepregnancy overweight and obesity, excessive GWG and GDM increased the risk of macrosomia significantly. The pairwise interactions of each pair of risk factors or all three risk factors on macrosomia appear to be greater than any of them individually. Prepregnancy overweight and obesity contributed the least (5.69%) to macrosomia, while GDM contributed the most (8.5%). The PAF values for prepregnancy overweight and obesity/GDM, excessive GWG/GDM, and prepregnancy overweight and obesity/ excessive GWG were 13.6%, 16.25% and 14.45%, respectively, and the total PAF for all three risk factors was 22.63%. Conclusions: Prepregnancy overweight and obesity, excessive GWG and GDM were associated with newborn macrosomia.