Association of maternal folate and vitamin B12 in early pregnancy with gestational diabetes mellitus: a prospective cohort study
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.