In contrast , we did not find any beneficial effect of  folate supplementation on placental weight or on length of gestation .
There is a paucity of well-conducted RCTs investigating the effect of  folate supplementation on health outcomes in pregnancy .
The beneficial effect of folic acid supplementation before and shortly after conception is well recognized , whereas the effect of supplementation during the second and third trimesters is controversial and poorly documented .
Our aims were to systematic ally review r and omized controlled trials ( RCTs ) investigating the effect of folate supplementation on birth weight , placental weight and length of gestation and to assess the dose – response relationship between folate intake ( folic acid plus dietary folate ) and health outcomes .
Reduction of Incidence of Prematurity by Folic Acid Supplementation in Pregnancy
Folic acid administered to pregnant Bantu , whose diet is low in folate , was associated with a significant reduction in the incidence of prematurity . No such effect could be demonstrated in White patients subsisting on an average Western diet . This suggests that folate deficiency may contribute to the “ pregnancy wastage ” in population s whose dietary folate intake is low , and is a further indication for folic acid supplementation during pregnancy in these groups
In contrast , we did not find any beneficial effect of  folate supplementation on placental weight or on length of gestation .
There is a paucity of well-conducted RCTs investigating the effect of  folate supplementation on health outcomes in pregnancy .
The beneficial effect of folic acid supplementation before and shortly after conception is well recognized , whereas the effect of supplementation during the second and third trimesters is controversial and poorly documented .
Our aims were to systematic ally review r and omized controlled trials ( RCTs ) investigating the effect of folate supplementation on birth weight , placental weight and length of gestation and to assess the dose – response relationship between folate intake ( folic acid plus dietary folate ) and health outcomes .