Abstract
The essentiality of folate and vitamin B12 for the synthesis of DNA may interfere with a successful pregnancy outcome when the mother is deficient in these micronutrients. The objective of this paper is to assess the effects of folate and vitamin B12 deficiencies on pregnancy outcomes, other than neural tube defects (NTD), and the effects of these deficiencies on infant and child development.
Supplementation studies identified by two Cochran Reviews were selected to assess the impact of folate deficiency on pregnancy outcomes, and a systematic review of the literature was used to assess their effects on infant and child developments.
Folate supplementation consistently resulted in improvement of hematological and folate status indicators. Seven supplemental studies consistently found no differences in the risk of total fetal loss, early or late miscarriage, stillbirth, preeclampsia, perinatal death, neonatal death, preterm birth, small-for-gestational age, or infant death in supplemented women compared with their controls. Two of those studies found greater placental weights (difference 96 g; 95% CI, 30.7 to 161.2 g), birthweights (difference 312 g; 95% CI, 108.5 to 515.4 g), and a lower risk for newborns weighing < 2,500 g in supplemented women (RR = 0.94; 95% CI, 0.90 to 0.99). Abnormal vitamin B12 and homocysteine serum concentrations were more readily associated with poor pregnancy outcomes. The very few studies addressing the effects of folate and vitamin B12 deficiencies on infant and child development were inconclusive.
Early supplementation with folate to pregnant women improves hematological and folate status indicators, but has little or no effect on pregnancy outcomes, other than on NTD. Vitamin B12 deficiencies and low homocysteine are more readily associated with poor pregnancy outcomes.