Does pregnancy change the mother's epigenetic age?
Whether pregnancy is beneficial or detrimental to the mother's health is an age-old dispute. There are two main theories concerning this: the regeneration theory and the disposable soma theory.
The regeneration theory suggests that pregnancy is beneficial to the mother because it may regenerate the mother's organs. Pregnancy is similar to heterochronic parabiosis, whereby beneficial factors from the young are transferred to the older person – these factors promote good health and longevity.
The disposable soma theory suggests that pregnancy is detrimental to the mother's health. This theory indicates that pregnancy has high costs, which compromise maternal longevity. Maternal resources are used to develop the child, which subsequently advances the maternal age.
Epigenetic alterations are a hallmark of ageing. That's why researchers developed epigenetic clocks based on epigenetic alterations. Researchers can determine an individual's epigenetic age by using these clocks; this can identify if an individual has accelerated ageing. The epigenetic clocks can be used to determine whether pregnancy accelerates ageing or not.
In one study, researchers found that the epigenetic age increased with young women's gravidity – It's also important to note that their telomere length had decreased with gravidity. In another study, researchers determined that each pregnancy accelerated the epigenetic age of young women. In the study, three epigenetic clocks were used (Hannum, Horvath, and Levine clocks).
So, it seems that having more children increased the women's epigenetic age, which would suggest that the pregnancies made them age. However, it might not be that simple. So, we need to find out whether the epigenetic age increases in various conditions. I have compiled some research ideas to use for future studies.
The studies above determine the epigenetic age of young women aged 20-22 years old with gravidity. The same research should be conducted but with more senior women to see if their epigenetic age also increases with gravidity.
Does the epigenetic age of women change throughout pregnancy, i.e. before, during, and after pregnancy?
Compare the epigenetic ages of women that have one birth to those that have multiple deliveries at the same time, i.e. twins, and triplets.
Find out whether mothers from three different age groups (18-25, 26-35, and 36-45) have similar epigenetic ages throughout their pregnancy (before, during, and after pregnancy)
Can you think of any more research ideas? Does pregnancy increase or decrease the mother's epigenetic age?
Michaeli, Tal Falick, Yehudit Bergman, and Yuval Gielchinsky. "Rejuvenating effect of pregnancy on the mother." Fertility and Sterility 103.5 (2015): 1125-1128.
Ziomkiewicz, Anna, et al. "Evidence for the cost of reproduction in humans: high lifetime reproductive effort is associated with greater oxidative stress in post-menopausal women." PloS one 11.1 (2016): e0145753.
Armstrong, Nicola J., et al. "Aging, exceptional longevity and comparisons of the Hannum and Horvath epigenetic clocks." Epigenomics 9.5 (2017): 689-700.
Ryan, Calen P., et al. "Reproduction predicts shorter telomeres and epigenetic age acceleration among young adult women." Scientific reports 8.1 (2018): 1-9.
Kresovich, Jacob K., et al. "Reproduction, DNA methylation and biological age." Human Reproduction 34.10 (2019): 1965-1973