If pressed to name the two most notable health-related statistics, lifespan and number of children may come to mind. Few metrics encapsulate the story of human life as well as these do. According to Statista, the average American man lives 77 years and the average American woman lives 81 years, whereas the average American parent bears two children.
For those who have experienced the joys and challenges of raising children, it’s easy to wonder whether this experience has affected lifespan. (Stepping on Legos detracts at least a year from life, right?) Empirically, at least, a mixed relationship exists between these two variables.
In a retrospective study involving the Amish, researchers used genealogical data to look at 2,015 individuals whose children were born between 1749 and 1912 to determine the association between parity (ie, number of children) and longevity.
The investigators found that the lifespan of fathers increased linearly by 0.23 years for every additional child. Similarly, lifespan increased linearly in women having up to 14 children. After 14 children, this correlation dropped off. (Having 14 children must be stressful for anyone!). The association in women was rooted in a later age at last birth.
“Our data reveal a positive correlation between number of offspring and lifespan,” the authors concluded. “The correlation may be an indirect one, arising from the fact that healthy individuals are more likely to have large numbers of offspring and to experience a longer life span. There might also be social and/or biological attributes associated with high parity that promote longer life.”
According to the results of a prospective analysis of the Women’s Health Initiative published in the American Journal of Public Health, researchers found that later maternal age at first childbirth was linked to increased odds of living to 90 years in older women. Women who took two pregnancies to term had a higher chance of living longer versus nulliparous women. Moreover, White (but not Black) women with two to four term pregnancies vs one term pregnancy lived longer.
“The higher likelihood of longevity among women with two to four term pregnancies may be partly explained by better overall health in those who are capable of childbearing compared with nulliparous or primiparous women,” the authors wrote. “Alternatively, the association may be explained by residual confounding attributable to SES (socioeconomic status), early life factors, or lifestyle factors. For example, a previous study observed that, among women, the number of children was linearly associated with adult socioeconomic indicators (eg, social class, car ownership, and housing tenure) and childhood social class.”
They added, “The inverse association between high parity and longevity in Black women may be attributable to weight gain with numerous pregnancies.”
Of note, researchers balanced these results for demographic characteristics, SES, lifestyle behaviors, reproductive factors, and health-related factors.
According to the authors of a study published in the European Journal of Population, recent meta-analyses utilizing contemporary data demonstrated a J-shaped relationship between longevity and parity. Specifically, mortality is higher in childless men and women, lowest in mothers/fathers with two children, and then rises again. The authors suggested various mechanisms—protective and detrimental—underlying the associations.
For instance, biomedical models point to the chances of increased health problems tied to pregnancy, childbirth, and lactation. These include breast, ovarian, and uterine cancer in women.
“Key amongst these processes is the role that ovarian hormones play,” the authors wrote. “Ovarian hormones, particularly progesterone and estrogen, stimulate cell growth, including the growth of cancerous tissues. Women are amenorrheic during pregnancy and lactation. As a result, women with children and who breastfeed experience fewer menstrual cycles than childless women, and repeated childbearing particularly reduces the cumulative exposure to progesterone and estrogen.”
With respect to evolutionary theories, the authors cited a direct exchange between childbearing and longevity: Those who bear children are drained of physiologic reserves. Such hypotheses apply to men and women who incur costs in life energy depending on their contributions to childcare.
Lastly, having children can extend life if children contribute to parental health and well-being in older age.
“The social support model emphasizes the potential support, both social and financial, that children can provide to parents in their post-reproductive years. Recent research has shown that the socioeconomic status of children is associated with parental mortality, which may be attributable to the extent to which children are able to direct time and resources to help their aging parents,” the authors wrote.
They added that having more children may be linked to increased social support in aging parents. These benefits are compounded when adult children live nearby and dedicate time to helping their parents. Importantly, the authors found that daughters are more likely to live near and care for ailing parents.
Parents invest incalculable resources into the success of their offspring. It’s affirming that this investment doesn’t come at the high cost of fewer years spent on earth—especially in those who have more children. With this in mind, feel free to do the deed and breed.