Association of maternal folate and vitamin B12 in early pregnancy with gestational diabetes mellitus: a prospective cohort study
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To investigate the association of folate and vitamin B12 in early pregnancy with gestational diabetes mellitus (GDM) risk.
RESEARCH DESIGN AND METHODS
The data of this study were from a sub-cohort within the Shanghai Preconception Cohort Study. We included pregnancies with red blood cell (RBC) folate and vitamin B12 measurements at recruitment (between 9-13 gestational weeks) and those with three samples available for glucose measurements under oral glucose tolerance test (OGTT). GDM was diagnosed between 24-28 weeks gestation. Odds ratio (OR) of having a GDM and 95% confidence interval (CI) was used to quantify the association.
A total of 1,058 pregnancies were included and 180 GDM occurred (17.01%). RBC folate and vitamin B12 were significantly higher in pregnancies with GDM than those without GDM (P values were 0.045 and 0.002 respectively), and positively correlated with 1-hour and 2-hour serum glucose. Daily folic acid supplementation in early pregnancy increases the risk of GDM, OR (95% CI) was 1.73 (1.19-2.53), P=0.004. Compared with RBC folate <400 ng/mL, pregnancies with RBC folate ³600 ng/mL was associated with approximately 1.60-fold higher odds of GDM, the adjusted OR (95% CI) was 1.58 (1.03-2.41), P=0.033. A significant trend of risk effect on GDM risk across categories of RBC folate was observed (Ptrend =0.021). Vitamin B12 was significantly associated with GDM risk (OR =1.14 per 100 pg/ml, P=0.002). No significant association of serum folate and percentile ratio of RBC folate/vitamin B12 with GDM was observed.
Higher maternal RBC folate and vitamin B12 levels in early pregnancy are significantly associated with GDM risk, while the balance of folate/vitamin B12 is not significantly associated with GDM.