Vitamin A supplementation during pregnancy

All randomized or quasi-randomized trials that evaluated the effects of vitamin A supplementation in pregnant women were included in the review. However, since the trials in the review were heterogeneous with regard to type of supplement given, duration of supplement provided and the outcomes measured, their results could not be pooled for meta-analysis. Also, the review did not include studies that examined the possible beneficial effects of vitamin A supplementation in HIV pregnant women. The review is unbiased and rigorous, but owing to the limitations of the included trials, the authors could not conclude whether vitamin A supplementation had a clear impact on maternal mortality.

A large study from Nepal examined the effects of vitamin A supplementation on the reduction of pregnancy-related and direct mortality occurring within 12 weeks post partum, including injury-related deaths. The study reported a reduction in mortality for all cases in the supplementation groups (40% in the vitamin A group and 50% in the beta-carotene group). The combined effect of these two forms of supplementation was 44% reduction in pregnancy-related deaths. However, beta-carotene (pro-vitamin A) has significant anti-oxidant properties that are not present in vitamin A. As this may have implications for specific pregnancy complications such as pre-eclampsia/eclampsia, the pooling of the results may not be appropriate.

A nested case-control study within this trial found a significant reduction in night blindness. It could be speculated that this reduced prevalence of night blindness may have accounted for the observed reduction in maternal deaths from physical injuries in the trial.

Fetal or early infant survival was not improved by supplementation.

Anaemia

Three studies examined the effect of vitamin A supplementation on haemoglobin levels. A study from Indonesia showed that in anaemic women (Hb<11.0g/dl), supplementation reduced the proportion of pregnant women with anaemia. After supplementation, the proportion of women who became non-anaemic was 35% in vitamin A supplementation group, 68% in the iron supplemented group, 97% in the group supplemented with both vitamin A and iron, compared with 16% in the placebo group. These results suggest that vitamin A and iron combination may be more effective than either iron or vitamin A alone in treating mild anaemia in pregnancy.

Two studies from Malawi also investigated the effects of vitamin A supplementation on treatment of anaemia in pregnancy. However, rather than the factorial design used in the Indonesian study, this study compared vitamin A supplementation with placebo in a cohort of women already using iron and folic acid as part of routine antenatal care. There was no significant difference in levels of haemoglobin between women receiving vitamin A supplementation and controls. This study also reported high rates of loss to follow-up.

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