Birth weight and the effects of birth spacing and breastfeeding on infant mortality.

Analyses previously reported, based on data from the World Fertility Survey (WFS), are replicated here with data from the Malaysian Family Life Survey. Comparison of results, when data limitations inherent in the World Fertility Surveys are reproduced or relaxed, suggests that these limitations cause little distortion, and thus bolsters confidence in the validity of results based on WFS data in which these limitations are inescapable. Generalizations based on the present investigation and on the body of previous work that it tends to validate are presented. Most significantly, these include the greater importance of both breastfeeding and birth spacing under generally unfavorable conditions, the variability of durations to which some benefit of continued breastfeeding persists, and the observation that the great majority of birth-spacing effects operate through some mechanism other than the association of breastfeeding with birth interval lengths.