Objective: Our aim in this study was to assess the association between folic acid (FA) supplementation before and during pregnancy and risk of gestational diabetes mellitus (GDM) in Chinese women.
Methods: This case-control study was conducted at 2 hospitals in central China. A total of 1,300 pregnant women, including 396 GDM patients and 904 controls, participated in the study. Information on the dose and duration of FA supplementation was collected using a self-report questionnaire at enrolment (24 to 28 weeks of gestation).
Results: We observed a U-shaped association between FA supplementation and GDM risk that demonstrated a 228% increased risk of GDM among women who never took FA supplements, a 28% increased risk among women who took supplements containing <400 μg/day FA or took FA supplements for <1 month and a 188% increased risk among women who took supplements containing ≥800 μg/day FA for an adequate duration (>1 month before pregnancy and >3 months during pregnancy) compared with women who took supplements containing 400 to 799 μg/day FA for an adequate duration (all p<0.05). For women who took supplements containing ≥800 μg/day FA for an adequate duration, the association between FA supplementation and GDM risk appeared to be stronger among those women with a prepregnancy body mass index (BMI) of ≥25 kg/m2 than among those with a prepregnancy BMI of <25 kg/m2 (p=0.006 for interaction).
Conclusions: There was a U-shaped association of FA supplementation with GDM risk; that is, FA supplementation both below and above the recommended levels may increase the risk of GDM.
Keywords: acide folique; diabète sucré gestationnel; folate; folic acid; gestational diabetes mellitus; grossesse; micronutrient; micronutriment; pregnancy.
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