Higher folate intakes during pregnancy may lower the risk of preterm birth

A new study from Singapore suggests that increased maternal folate concentrations during late pregnancy seem to be associated with longer gestational age and a lower risk of preterm birth.

The observational study measured the blood concentrations of folate, vitamin B12 and vitamin B6 in 999 women in the 26th–28th weeks of gestation as well as birth weight and gestational age of their babies (1). The study results showed that higher plasma folate concentrations were associated with a longer gestational age and tended to be associated with lower risk of all preterm birth (delivery earlier than 37 weeks gestation) and spontaneous preterm birth. Little or no benefit was measured of higher vitamin B6 and vitamin B12 concentrations for reducing the risk of preterm birth.

The researchers commented that several recent cohort studies in Western countries also suggested that higher maternal folate concentrations (mainly measured during early pregnancy) were associated with longer gestational age or lower preterm birth risk (2, 3). A review of 3 clinical trials concluded that folic acid supplementation starting at mid- or late pregnancy through delivery had no effect on preterm birth risk (4). Nonetheless, the authors of the review commented that their findings were likely to have been influenced by bias and confounding due to methodological limitations of the original studies. There is an increased requirement for folate intake and folate-containing supplement use during pregnancy due to rapid maternal and fetal cellular growth and development. Folate plays critical roles in nucleotide (purine and thymidine) synthesis, which can subsequently affect DNA synthesis and mitotic cell division.

1. Chen L.-W. et al. Maternal Folate Status, but Not That of Vitamins B-12 or B-6, Is Associated with Gestational Age and Preterm Birth Risk in a Multiethnic Asian Population. J. Nutr. Published online November 2014.
   
   
2. Bergen N. E. et al. Homocysteine and folate concentrations in early pregnancy and the risk of adverse pregnancy outcomes: the Generation R Study. BJOG. 2012; 119:739–751.
   
   
3. Bodnar L. M. et al. Maternal serum folate species in early pregnancy and risk of preterm birth. Am J Clin Nutr. 2010; 92:864–871.
   
   
4. Lassi Z. S. et al. Folic acid supplementation during pregnancy for maternal health and pregnancy outcomes. Cochrane Database Syst Rev. 2013; 3:CD006896.