In summary, we conducted a retrospective study based on 5614 mother-infant pairs in Chinese population to explore the association of pre-BMI and MTHFR genotypes with the risk of adverse pregnancy outcomes, indicating that a higher pre-BMI (≥ 24.0 kg/m2) in pregnant women was positively related to the risk of GDM, GHT, and CS. The gene discussed is MTHFR; the disease is gestational diabetes.