Sign up for Today in Science, a free daily newsletter from Scientific American and join a community of science-loving readers.<\/a><\/p>\nHukkanen and her colleagues analyzed data from the Finnish Twin Cohort, a project that has tracked the health of thousands of twin pairs since 1974. They separated 14,836 women from this cohort into six groups based on the number and timing of their childbirths (allowing them to compare genetically similar parents). Then, using lifespan data and blood samples showing aging-linked DNA changes, the researchers modeled how reproduction impacted the aging process of women in each group.<\/p>\n
In line with previous findings, members of the cohort who had the most children tended toward shorter lifespans and faster epigenetic aging\u2014changes to how DNA is expressed later in life. This fits with a major evolutionary biology theory known as \u201cdisposable soma theory,\u201d which suggests that when organisms put more resources into one aspect of life\u2014such as growth, reproduction or bodily maintenance\u2014it comes at the expense of other areas. Thus, if more resources go to reproduction, it could mean that less time and energy and fewer nutrients are available for maintenance functions such as DNA replication and repair.<\/p>\n
The finding that people who didn\u2019t have children also aged faster and had shorter lifespans was more surprising, Hukkanen says. Other researchers in the field say this U-shaped curve representing the relationship between reproduction and aging fits with the data, however.<\/p>\n
\u201cI\u2019m seeing more and more [studies] on different measures of aging, and [they\u2019re] starting to converge on the pattern that you see here,\u201d says Calen Ryan, a population epigeneticist at Columbia University, who was not involved in the study.<\/p>\n
Some aspects of pregnancy and childrearing are protective of health, lowering the risk of some cancers; for example, breastfeeding lowers the risk of breast and ovarian cancer. Additionally, the increased social support that some parents get when their children are young and the caregiving that they may get from their children later in life may increase their longevity. These benefits might be part of the reason women who did not have children aged faster. But for parents of more than four children, the biological costs may outweigh the benefits.<\/p>\n
While the U-shaped curve helps to illuminate how birth and childrearing impacted the study cohort\u2019s aging, the findings don\u2019t necessarily translate to people choosing whether to have kids today, the study authors explain. \u201cI really want to emphasize that this is not a prescription for anyone on how to have your children,\u201d Hukkanen says. \u201cWe are just seeing associations and links…. It\u2019s not directly applicable to women having children right now.\u201d<\/p>\n
The study focuses on a historical cohort with much different life circumstances than people who might become pregnant today. The participants were born between 1880 and 1957, and some of them lived through several wars and periods of social upheaval in Finland that could have impacted both their health and their opportunities to have children. Also, choosing to be child-free was far less common when members of the study cohort were having children, Hukkanen says, so childlessness in the study might have been more frequently tied to preexisting health conditions that could also impact aging and lifespan.<\/p>\n
For people choosing whether to have children today, researchers say differences in social circumstances, health care access and high-quality research on reproductive health could make a big difference on how having\u2014or not having\u2014children impacts the body and aging process. \u201cWith the advent of some of these tools to quantify biological aging, we\u2019re starting to be able to measure the impacts of pregnancy in much shorter timescales, which I think is exciting,\u201d Ryan says. \u201cIt not only allows us to possibly predict who might be at risk, it also opens the door for clearer pathways to interventions.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"Numerous factors affect how fast we age, from the environment down to our DNA. Even the number of…\n","protected":false},"author":2,"featured_media":426143,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[34],"tags":[166706,16713,97,83616,202735,22961],"class_list":["post-426142","post","type-post","status-publish","format-standard","has-post-thumbnail","category-health","tag-aging-process","tag-evolutionary-biology","tag-health","tag-historical-data","tag-mikaela-hukkanen","tag-reproduction"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/426142","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=426142"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/426142\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/426143"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=426142"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=426142"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=426142"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}