Effects of birth rank, maternal age, birth interval, and sibship size on infant and child mortality: evidence from 18th and 19th century reproductive histories.

There has been long-standing interest in the effects of maternal age, birth rank, and birth spacing on infant and child mortality. Contradictory inferences about the role of these factors have arisen on occasion because of the absence of adequate controls, the use of cross-sectional or incomplete reproductive histories, and inattention to the effect of family size goals and birth limitation practices. This study analyzes completed reproductive histories for German village populations in the 18th and 19th centuries, a period when deliberate fertility control was largely absent. Our results confirm previous studies of the association of infant mortality with maternal age, although in the present data these differentials are largely limited to neonatal mortality. They also confirm the importance of birth interval as a factor in infant mortality. Sibship size is positively related to infant mortality even when birth rank is controlled. However, once sibship size is controlled, there are no systematic differences in infant and child mortality by birth order. The mechanisms relating sibship size and mortality are explored.