Kai Willfuehr , University of Oldenburg
This study investigates the impact of kinship on fertility in the historical population of the Krummhörn region in Germany [1720 – 1875]. Poisson regression analysis is used to investigate the effect of time shared between 4,807 reproductive females and their biological parents as well as parents-in-law on the absolute number of births and surviving children. Models with a minimum set of control variables suggest that biological parents and the mother-in-law are associated with higher fertility. However, this association is not suggested, if the models control for the time period women are married before the age of 45. In a more sophisticated approach, multiple-failure Cox regression analysis is used to model the effect of kin on inter-birth intervals. This approach relies on a combination of models adjusted by clustering at the family level, and models stratified at the family level. Beside the parents and parents-in-law, time-varying information about the availability of siblings and siblings-in-law are included in the models. The results of the Cox regression analysis suggest that fertility of married females was not affected by kinship or by kin present in the same parish of residence. This study is line with other studies using historical data from Europe which also suggest that kin availability was not a significant factor for fertility. It is argued that kinship might have been more important regarding marriage formation in demographic saturated population, whereas kin might directly promote fertility in demographically expanding populations.
Presented in Session 23. Historical Demography