Exploring associations between parenthood and biological ageing using epigenetic clocks

Parenthood is a major life event involving physiological impacts on women and significant lifestyle changes for mother and father. Stressors involved in both producing and rearing children are potentially important influencers of biological ageing. One way of measuring this potential parenthood-ageing relationship is using epigenetic clocks. Based on DNA methylation changes, these have emerged as an accurate method for measuring biological age. However, there is limited research on the relationship between parenthood and epigenetic ageing and which considers both reproductive and child rearing ‘effort’.

Using data from Understanding Society, the DunedinPACE third-generation epigenetic clock, and multivariable linear regression methods, this study investigates associations between parenthood and epigenetic ageing. It uses an expanded interpretation of parenthood, incorporating exposures on both reproductive and childrearing ‘effort’, adjusting iteratively using demographic and socioeconomic covariates, and introducing interaction terms to explore sex differences between parenthood-ageing associations.

In fully adjusted models, both reproductive and childrearing exposures were associated with an accelerated pace of epigenetic ageing for parents compared to non-parents and for those who currently live with their children versus those who do not. The pace of ageing was also accelerated with greater parity, number of children in the household and younger parental age. Additionally, when comparing parents to non-parents, age-acceleration associations were found to be stronger in males than females.

Although the age-acceleration associations of parenthood, parity and younger parental age align with previous work, findings on the male-female balance of this association differ, and the addition and significance of rearing ‘effort’ exposures extends understanding of the parenthood-ageing relationship. They suggest that the longer-term social effects of parenthood on ageing are potentially as important as the shorter-term physiological impact of reproduction. This has implications for public health initiatives on ‘healthy ageing’ and policy related to family planning and gender related health equality.