Birth interval and family effects on postneonatal mortality in Brazil.

In this paper random-effects logistic models are used to analyze the effects of the preceding birth interval on postneonatal mortality in Brazil, controlling for the correlation of survival outcomes between siblings. The results are compared to those obtained by using ordinary logistic regression. Family effects are found to be highly significant in the random-effects model, but the substantive conclusions of the ordinary logistic model are preserved. In particular, birth interval effects remain highly significant.