Reproduction, Stress, and Resilience
Studying pregnancy, physiological stress, and biological aging across the life course
Past Work
My work on reproduction and aging grew from evolutionary life history theory and the idea that reproduction can involve tradeoffs with somatic maintenance. In the Cebu Longitudinal Health and Nutrition Survey, I studied whether reproductive history was associated with molecular measures of biological aging in young women.
This work showed that pregnancy is linked to faster epigenetic aging in young women. Related work found that immune-cell composition and DNA methylation vary with reproductive status, suggesting possible pathways linking pregnancy, lactation, immunity, and later-life health. In parallel, work with Shirazi and colleagues showed that parity predicted clinical biological age acceleration among post-menopausal women.
Current Work
I now frame pregnancy as a model of both aging and resilience: a period of intense physiological demand that may reveal mechanisms of vulnerability, repair, recovery, and long-term health. This includes work on maternal stress and fetal/placental epigenetics, as well as ongoing CLHNS work on chronic stress biology and epigenetic aging.
I am also developing work that uses electronic health record laboratory measures to study biological reserve, recovery, and resilience after cardiothoracic surgery.
Future Work
An important direction in this area is the long-term health of women after adverse pregnancy outcomes. I am planning projects focused on how pregnancy complications may forecast later-life health and aging, without treating pregnancy as an isolated clinical event.
My grant on reproduction and Alzheimer’s disease and related dementias (ADRD) extends my earlier studies of reproductive costs and biological aging toward later-life cognitive aging, resilience, and women’s health.
Selected References
Ryan CP, Lee NR, Carba DB, et al. Pregnancy is linked to faster epigenetic aging in young women. Proceedings of the National Academy of Sciences. 2024;121:e2317290121.
Ryan CP, Jones MJ, Edgar RD, et al. Immune cell type and DNA methylation vary with reproductive status in women: possible pathways for costs of reproduction. Evolution, Medicine, and Public Health. 2022;10:47-58.
Shirazi TN, Hastings WJ, Rosinger AY, Ryan CP. Parity predicts biological age acceleration in post-menopausal, but not pre-menopausal, women. Scientific Reports. 2020;10:20522.
Post SR, Ryan CP, Lee NR, et al. Patterns of chronic stress in diurnal salivary cortisol already predict epigenetic age acceleration in young adults in the Cebu Longitudinal Health and Nutrition Survey. American Journal of Human Biology. 2026;38:e70290.