The Association between Maternal B Vitamins in Early Pregnancy and Gestational Diabetes Mellitus: A Prospective Cohort Study

Background: This study evaluated the association between maternal B vitamins in early pregnancy and gestational diabetes mellitus (GDM) risk. Methods: A cohort of 1265 pregnant women was recruited at 8-15 weeks of gestation in 2021-2022 (Shanghai, China). Pregnancies with both serum B vitamin measurements at recruitment and glucose measurements at 24-28 weeks of gestation were included in the final analysis. Results: Of the 1065 pregnancies, in the final analysis, GDM occurred in 121 women (11.36%). In multivariate logistic models, an increased risk trend across serum vitamin B-1 quartiles with GDM was observed (p-Trend = 0.001). Compared with women in the lowest quartile of serum vitamin B-6, those in the upper two quartiles had approximately twofold higher odds of GDM. Moreover, compared with women with vitamin B-12 levels < 150 pmol/L, those with vitamin B-12 levels > 150 pmol/L had lower odds of GDM (p = 0.005). The restricted cubic spline regression models also revealed that serum vitamin B-6 and vitamin B-12 were associated with an increased risk of GDM in a nonlinear fashion. Conclusions: Our study shows that higher maternal serum vitamin B-1 and B-6 levels in early pregnancy are associated with increased GDM risk, while sufficient vitamin B-12 status is associated with lower GDM risk.