The data were entered into a desktop computer and edited using a software EPI Info (CDC, Atlanta, USA and WHO, Geneva) and analyzed by EPI Info and another software named Stata (Stata Corporation, Texas, USA). The main comparison was between those who received zinc and those who received placebo. Baseline information was compared to evaluate the comparability of the two groups. These include socio-economic variables, type of delivery, gestation, birth weight, breast-feeding status etc. The two groups were compared for all-cause mortality. The proportion of infants having illness requiring hospitalization in the two groups was compared. For this comparison, only the first episode requiring hospitalization in a particular infant was considered. Although the follow-up period would be very similar, some degree of variable follow-up was expected which was addressed by using person-time calculation between 4 weeks and end of the study. The analysis was based on intention-to-treat.