Five publications reporting data on 4 RCTs involving 2,863 pregnant women and 2,620 births were included.
Three studies described how the randomisation sequence was generated, two reported concealment of treatment allocation, one study reported on blinding, four reported that informed consent was obtained, four reported an a priori sample size estimation, and three used an intention-to-treat analysis. All studies disclosed sources of funding.
Vitamin A (3 RCTs, 2,503 women and 2,268 births).
One study suggested that vitamin A supplementation increased MTCT; the other two reported no effect of treatment. Overall, there was no significant difference in MTCT with vitamin A supplementation compared with placebo (RR 1.05, 95% CI: 0.78, 1.41, p=0.2), but there was significant heterogeneity in this analysis (p=0.01; I-squared 75%).
One study suggested that vitamin A supplementation decreased pre-term delivery, while another reported no effect of treatment. Overall, there was no effect on pre-term delivery (RR 0.85, 95% CI: 0.53, 1.37, p=0.5), but again there was significant heterogeneity (p=0.03; I-squared 77%).
Three studies reported no difference in child mortality at 1 year between vitamin A and placebo (RR 1.05, 95% CI: 0.88, 1.27, p=0.5). There was no evidence of heterogeneity (p=0.8; I-squared 0%).
Multivitamins (2 RCTs, 1,438 participants).
Both studies suggested that multivitamins may reduce pre-term delivery but the results were not statistically significant. Overall, multivitamin supplementation had no significant effect on pre-term delivery compared with placebo (RR 0.88, 95% CI: 0.73, 1.06, p=0.1; 2 studies). A single study also reported no significant effects on MTCT or child mortality at 1 year.