Pregnancy and Biological Aging

Pregnancy is characterized by extensive, energetically-costly changes across numerous physiological systems. These 'costs of reproduction' may accumulate with each pregnancy, accelerating biological aging. Despite evidence for costs of reproduction using molecular and demographic measures, it is unknown whether parity is linked to commonly-used clinical measures of biological aging.

According to a recent study, published in Scientific Reports, the number of times a person gives birth may affect how quickly they age. "Pregnancy and breastfeeding are accompanied by shifts in immune function, energy metabolism and storage, blood pressure and volume, and hormone levels and receptor expression. Evolutionary theory predicts that these changes create functional or energetic constraints to somatic maintenance and repair, leading to accelerated biological age—a tradeoff referred to as 'costs of reproduction," hypothesized the research team.

In the current study, researchers used data between 1999 and 2010 from the National Health and Nutrition Examination Survey (n= 4418) to test whether parity (number of live births) predicted four previously-validated composite measures of biological age and system integrity:

• Levine Method
• Homeostatic dysregulation
• Klemera–Doubal method biological age
• Allostatic load

Parity exhibited a U-shaped relationship with accelerated biological aging when controlling for chronological age, lifestyle, health-related, and demographic factors in post-menopausal, but not pre-menopausal, women, with biological age acceleration being lowest among post-menopausal women reporting between three and four live births.

Data Analysis

Data analysis revealed the following facts:

• The linear effect of number of live births and squared term, or quadratic effect, of live births was not significant in any primary model in pre-menopausal women.
• After correcting for multiple comparisons, the main effects of months since last live birth and parity was not significant in any model, nor were any of the interaction terms between months since last live birth and parity.
• Primary models in post-menopausal women revealed a significant linear effect of live births on biological aging indexed by LM, HD, and AL; the linear effect of live births on KDM was not significant after correction for multiple comparisons.

"Our findings suggest a link between reproductive function and physiological dysregulation, and allude to possible compensatory mechanisms that buffer the effects of reproductive function on physiological dysregulation during a woman's reproductive lifespan. Future work should continue to investigate links between parity, menopausal status, and biological age using targeted physiological measures and longitudinal studies," wrote the team.

For full article follow the link: 10.1038/s41598-020-77082-2

Primary source: Scientific Reports