Doctoral Dissertation Research: Quantifying the Costs of Human Reproduction using the 'Epigenetic Clock'

Northwestern University, Evanston IL

Investigators

Abstract

Research on non-human species suggests that female reproduction may come at a cost to maintaining and repairing the body, affecting both health and lifespan. Studies using historical records suggest a similar 'cost of reproduction' in human females, but are often confounded by unmeasured social and environmental factors that obscure causal relationships between reproduction and lifespan. This doctoral dissertation project will use a new measure of 'epigenetic age' to better understand these life history trade-offs in humans. By examining both reproduction and epigenetic age at several time points in a woman's life, social and environmental effects on aging can be accounted for, yielding a clearer picture of the costs of reproduction. Uncovering the molecular pathways responsible for costs of reproduction in women could inform new strategies for diagnosing and treating age-related diseases. This project will also support graduate student training and long-term research collaborations. The investigators will analyze data for 195 women who are part of the Cebu Longitudinal Health and Nutrition Survey to test whether those who have had more pregnancies show signs of more rapid biological aging during a 13-year period. The number of children, their sex, size, and birth spacing - as well as energy allocated to breastfeeding - will be calculated over the women's peak reproductive lives, and compared to the pace change in each woman's epigenetic age. Epigenetic age is calculated by counting chemical modifications made to DNA, and is a strong predictor of negative health outcomes and mortality across multiple populations. The researchers will also examine the relationship between reproduction and epigenetic age among 155 older women, for whom they will combine these data with a separate, comprehensive survey of age-related decline. This will be the first study to examine the effect of reproduction on epigenetic age in females, and will provide an important foundation for future studies aimed at clarifying the links between reproduction and late life outcomes in humans. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.