Evidence on birth spacing and child cognition from Indonesia

Research from the medical and social science literature has found that spacing births closely together leads to adverse health and socioeconomic outcomes for the younger child. More recent evidence using inter-family comparisons is challenging the validity of those results. However, while inter-family comparisons allow for time-invariant unobservable heterogeneity across families, they cannot fully control for changes in families that occur over time and may affect both decisions about birth intervals as well as child outcomes. To our knowledge, this paper provides the first examination of the effects of birth spacing on later childhood cognitive outcomes that accounts for both time-invariant and time-varying heterogeneity in the same models. Instrumental variables estimations on data from Indonesia indicate that younger siblings perform significantly better on maths assessment exams when they are spaced farther apart from their immediately older sibling. This effect appears to be concentrated among the poorest and least educated households. The data thus suggest that close spacing may be detrimental to the socioeconomic outcomes of the younger sibling.