Do Younger Wives Increase Male Fertility? Evidence from the Historical Population of the St. Lawrence Valley

Andreas Filser, Institute for Employment Research (IAB)
Kai Willfuehr, University of Oldenburg

Until around 1730, the population of the St. Lawrence valley was predominantly male. An earlier study revealed that women married earlier when sex ratios where male-skewed and that female ages at first marriage increased as the sex ratio became more balanced. Male ages at first marriage remained approximately the same throughout the study period (1680-1750). Consequently, women spent longer lifespans in marriages before menopause as long as sex ratios were male-skewed. Given that fertility was limited to marriage, women entered their reproductive lifespan earlier. This has also implications for male fertility because it relies on the reproductive lifespan of females. Therefore, we expect male total fertility to be lower when wives are older at marriage. Cox and Poisson regression results indicate that male fertility is not associated with female ages at marriage. Preventing maternal mortality as well as fertility enhancement via kin networks could explain our findings. Kin networks were emergent during the early days of the colony. Early settlers had neither parents nor grandparents present. Emerging kinship networks could have facilitate narrower birth intervals, counterbalancing the decrease in female reproductive lifespan. Future analysis will further investigate kinship network composition and proximity to disentangle these potential explanations.

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 Presented in Session 111. Fertility Change, Timing, and Marriage