Vitamin supplementation for preventing miscarriage.

Study answer

What this study found

Overall, vitamin supplementation before conception or in early pregnancy did not prevent miscarriage. Vitamin C with vitamin E showed no effect on total fetal loss, early or late miscarriage, stillbirth, or adverse effects, and vitamin A, beta-carotene, vitamin C alone, folic acid, and most multivitamin comparisons also showed no clear benefit. The main exception was multivitamins plus iron and folic acid, which reduced stillbirth versus iron and folate alone (RR 0.92, 95% CI 0.85 to 0.99; 10 trials, 79,851 women), but did not reduce total fetal loss or early/late miscarriage. A few…

Study & population

Systematic review and meta-analysis of randomized and cluster-randomized trials in women planning pregnancy or pregnant women, with supplementation started before 20 weeks' gestation.

Intervention

This review evaluated oral vitamin supplementation started before conception, periconceptionally, or in early pregnancy, including vitamin C alone or with vitamin E or multivitamins, vitamin A or beta-carotene, folic acid with or without multivitamins and/or iron, multivitamins plus iron and folic acid, and…

Key limitation

The evidence base was heterogeneous in vitamin type, dose, timing, and comparison groups, making indirect comparisons difficult.

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Original abstract