Birth spacing and infant mortality: evidence for eighteenth and nineteenth century German villages.

Data from an historical population in which fertility control was minimal and modern health services were mostly unavailable are used to show that there appears to have been a strong association between previous birth interval length and infant mortality, especially when the previous child survived. Although only imperfect proxies for breast-feeding practices and other potentially confounding factors are available for this population, the results suggest that the association between previous interval length and infant mortality in this population is not solely, or primarily, a function of differences in breast-feeding behaviour or socioeconomic status. Other factors, e.g. maternal depletion or sibling competition, are more likely to explain the observed association.