LAUSR

In this study, we find that children in Vietnam who were born in December of a given year have better health outcomes than those born in January of the following year. Children born in December are taller, heavier, and less likely to be underweight and suffer from stunted growth than those born in January of the following year, though these two groups of children differ in age by only 1 month. We argue that the effect of being born in December compared to January on children's health is translated through early preschool attendance. In Vietnam, children born in December are more likely to start preschool as well as primary school 1 year earlier than those born in January of the following year. Thus, the health benefit for a child born in December would come from earlier and longer exposure to preschool. Importantly, we find that the positive effect of preschool persists over time as children grow. A possible major reason why preschool attendance improves health is the nutrition provided for children in preschools.