A number of trials on maternal multi-micronutrient supplementation (MMS) have found a benefical effect on birth weight, but few have demonstrated a beneficial effect on infant survival. We examined the effect of two different preparations of antenatal MMS on fetal loss and under-2-years child mortality, as compared with iron-folic acid supplementation among 2,100 pregnant women in Guinea-Bissau. Women receiving a 1xRDA MMS preparation (consisting of 14 vitamins and minerals) had a marginally reduced risk of fetal loss (Relative risk (RR) 0.65, 95% CI 0.40; 1.05), and women receiving a 2xRDA MMS preparation had a similar effect (RR 0.67, 95% CI 0.42; 1.08), the pooled effect being 0.66 (95% CI 0.44; 0.99). None of the supplements reduced under-2-years mortality or the combination of fetal loss and under-2-years mortality. There was a marginally negative effect of both the 1xRDA (RR 2.10, 95% CI 0.99; 4.46) and the 2xRDA (RR 2.02, 95% CI 0.95; 4.32) MMS preparation on mortality specifically between 92-365 days of age.