Despite the importance for public policy design, there is still a lack of evidence in middle income countries regarding children’s in-utero health and their later success in life. This study exploits the variation between siblings and explore the effects of birthweight on later health and education outcomes. Findings suggest that low birthweight affects future endowments, including height, health status and cognitive skills, up to the average age of 17. Estimations also suggest an effect on grade repetition in the case of children with highly educated mothers, plausibly because such pupils reach higher educational levels, where differences in health endowments may translate into differences in achievement. Additional exploratory results offer evidence of compensation among richer parents, who invest more money in their less healthy offspring. This evidence is broadly in line with the international literature and suggests that health and education policies should be complemented with early interventions to reduce disparities in birthweight.