 Assuming a type I error of 5 2-sided, 80 power, an IMR-6 of 52.51000 in the placebo group, and a minimum detectable reduction of 30 in the vitamin A group, the sample size required in each group is approximately 2700 live births. If we assume a 10 loss to follow-up this brings the number required in each group to approximately 3000, or a total of 6000 live births. 