Vitamin E supplementation in pregnancy.

Systematic review and meta-analysis of randomized trials in pregnant women from 15 countries. The evidence base included 21 trials with 22,129 participants in active vitamin E arms, and 17 trials with 21,856 participants contributed data to the pooled analyses. Most trials tested vitamin E in combination with other supplements, mainly vitamin C, and several enrolled women at high risk of adverse pregnancy outcomes or from populations with low nutritional status.

Vitamin E supplementation was evaluated during pregnancy, usually as a daily oral antioxidant regimen combined with vitamin C. Reported regimens commonly used vitamin E 400 IU daily with vitamin C 500 mg to 1000 mg daily, although doses varied across trials and some studies used other antioxidants or different vitamin E doses. Vitamin E alone remained unavailable for meaningful pooled assessment.

Routine vitamin E supplementation during pregnancy, mainly in combination with vitamin C, did not improve the main pregnancy outcomes studied. It did not reduce stillbirth, neonatal death, preterm birth, preeclampsia, preterm or term prelabour rupture of membranes, or poor fetal growth. Vitamin E was associated with a reduced risk of placental abruption, but it may increase term prelabour rupture of membranes and abdominal pain. Overall, there is no convincing evidence of important benefit, and data for vitamin E alone are unavailable.

Most trials tested vitamin E together with vitamin C or other agents rather than vitamin E alone, limiting attribution to vitamin E itself. Trial populations, doses, and outcome reporting were heterogeneous, and demographic or baseline nutritional details were inconsistently reported. Some outcomes were based on relatively limited contributing data despite the large pooled sample, and several studies involved high-risk or geographically specific populations, reducing generalizability.