Folic acid supplements in pregnancy and birth outcome: re‐analysis of a large randomised controlled trial and update of Cochrane review

Abstract

Periconceptual folic acid prevents neural tube defects. The effect of folic acid taken throughout pregnancy is unclear, however. We re-analysed data from a large randomised controlled trial performed between 1966 and 1967 and combined the results with those from trials included in a Cochrane review. A total of 2928 women were randomised: 1977 were allocated to placebo, 466 to folic acid 200 microg/day and 485 to folic acid 5 mg/day. Folic acid supplementation was not associated with any difference in mean birthweight, placental weight or gestational age. When combined with trials in the Cochrane review folic acid at high doses was associated with reduced risk of low birthweight (pooled relative risk 0.73 [95% CI 0.53, 0.99]). We found no conclusive evidence of benefit for folic acid supplementation in pregnant women given from time of booking onwards.

Elevated Maternal Serum Folate in the Third Trimester and Reduced Fetal Growth: A Longitudinal Study

“…In a UK trial, pregnant women were supplemented daily with either 0.2 mg or 5 mg FA, from about 17 wk to delivery. There was no difference in birthweight in either group, compared to nonsupplemented controls (27). Furthermore, mandatory FA fortification of grain products in the US seems to have had little impact on the prevalence of low birthweight.…”

Stillbirths: what difference can we make and at what cost?

“…periconceptional period. 42 Folic acid supplementation or fortifi cation periconceptionally-ie, before pregnancy and during the fi rst 2 months of pregnancy-reduces the risk of neural tube defects (table 1), 18 which account for a small proportion of stillbirths. Furthermore, food fortifi cation with folic acid, a more practical inter vention before conception, would be the preferred intervention and could reduce the occurrence of neural tube defects by 41% (table 1).…”

How Does Folic Acid Supplementation Affect Serum Folate Concentrations in Pregnant Turkish Women?

“…Yet, these studies usually review non-homogeneous and poorly defined populations which are not stratified in terms of demographic, social, and clinical characteristics. Moreover, accurate assessment of food intake and correct determination of individual food components is difficult and unreliable in non-interventional dietary studies [10,19,20]. The second challenge is that isolated deficiencies of dietary components are rarely encountered.…”