The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

What can we predict from first birth interval?


Department of Epidemiology and Population Studies, Institute of Public Health

Saturday 3:45-4:00, Ballroom B Add to calendar

Objectives: Women should differ in their reproductive strategies according to their nutritional status. We tested a hypothesis that women who have a good nutritional status early in life, as indicated by a shorter waiting time to the first birth (first birth interval, FBI), are able to afford higher costs of reproduction than women who have worse nutritional condition.

Methods: We collected data on 377 women who got married between the years 1782 and 1882 in a natural fertility population in rural Poland. The study group was divided into tertiles based on the length of FBI.

Results: Women with the shortest FBI had a higher number of children (p = 0.005), higher number of sons (p = 0.01), and shorter mean inter-birth intervals (p = 0.06). Women who had ever given birth to twins had shorter FBI than women of singletons (20.1 and 26.1 months, respectively; p = 0.049). Furthermore, women with a shorter FBI, despite having higher costs of reproduction, did not have a different lifespan than women with a longer FBI.

Conclusions: Our results suggest that women who were in better energetic condition (shorter length of FBI), achieved higher reproductive success without reduction in lifespan. FBI reflects inter-individual variation which may result from variation in nutritional status early in life and thus may be a good predictor of subsequent reproductive strategy. We propose to use FBI as an indicator of women’s nutritional status in studies of historical populations, especially when information about social status is not available.

This study was supported by grants from the Estreicher Fund, the Wenner-Gren Foundation, Salus Publica Foundation, the Yale University Program in Reproductive Ecology, the National Science Centre (grant no. N N404 273440), and the Ministry of Science and Higher Education (grant Ideas Plus no. IdP2011000161).

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