Jan 24, 2026
3 min read
The authors of a recent study investigated the relationship between reproduction (number and timing of offspring), aging, and survival.
Effects of Birth on Parenthood
- The number and timing of pregnancies is one factor.
- According to the epigenetic clock and other data, childless women and women with many children age faster than women with two or three children.
- Having children earlier in life is associated with faster aging.
- This cohort study failed to demonstrate causality and confounding factors may be involved.
The authors of a recent study investigated the relationship between reproduction (number and timing of children), aging and survival.An analysis of seven distinct reproductive trajectories suggested that two groups, women with the highest number of live births and women without children, had accelerated aging and increased mortality risk [1].
To preserve the body or reproduce?
"From an evolutionary biology perspective, organisms have limited resources such as time and energy. When large amounts of energy are invested in reproduction, it is diverted from the body's maintenance and repair systems, which can reduce lifespan."
Previous studies examining this theory have generally focused on one variable of female reproduction: the number of children.However, bringing children is much more complicated.Some women have their first child in their teens, while others wait until their late 30s or 40s.Some have no children at all, others may have ten or more.This study acknowledged these facts and examined the effects of having children on aging in a more complex way.
The researchers used data on the timing and number of birth events from nearly 15,000 women born between 1880 and the mid-20th century.These data come from the Finnish Twin Cohort, a population-based study that also includes data on socioeconomic background and lifestyle factors.The researchers used advanced modeling techniques for groups of women based on their behavioral history of children, and this model suggested seven different trajectories (including childlessness).
The stakes are high
After adjusting for differences in life expectancy over time, the researchers found differences in survival rates for each class.They evaluated the highest mortality risk for women (average 6.8), live births (class 6) and women without children (class 0), and the results were similar between the samples.There is also a slightly higher risk for women who have had only a few births early in life.(Class 1 and, to a lesser extent, 2) when compared to Class 3, which was used as a reference.The strength of this association was weak but significant after adjustment for known factors, including BMI, smoking and alcohol use, and education.
These different birth trajectories are also associated with distinct epigenetic aging profiles, which better reflect the effects of birth on accelerating age before senescence.
First, the authors used GrimAge, an epigenetic clock known for its powerful ability to predict the time of death and its association with many age-related conditions.According to this clock and DNA methylation data from more than 1,000 women, women in class 1 age faster than women in classes 3, 4 and 5, which also includes women who give birth in their late 20s and early 30s.
When the data was adjusted for known risk factors, childless women aged one year faster than the fifth cohort, which included women who had fewer children (on average 2 children) but had those children later in life.However, the biggest difference in epigenetic age acceleration (1.35 higher epigenetic aging rate) was between the 6th grade, which had the largest number of children, and the 5th grade. The latter group was epigenetically younger.Grade 6 also had the highest rate of aging compared to grade 0 and grades 2-5 when the same analysis was performed using two different epigenetic clocks.
“A person who is biologically older than his or her calendar age is at greater risk of death,” says study leader Dr. Minna Olikainen. “Our results show that life history choices leave a lasting biological imprint that can be measured long before old age.”
"In one of our study, the kids are associated with the young biological old man. This is a natural pretension of the project, because of the nature of the formerly."
The connection between early mother, the speed of aging, and survival can also be driven by limited access to healthcare and overall worse socio-economic and economic status, leading to increased physical, emotional and economic stress in young mothers;However, this study did not directly examine this.
The researchers summarized that the patterns they observed, particularly increased risk of mortality and accelerated aging among childless women and those with many children, were consistent with previous studies that reported a U-shaped relationship between the number of children and health [2-5].
The effect on the number of children is perhaps not surprising, because reproduction requires a lot of money, which hinders physical maintenance and reproduction.However, the difference can be expected from women without children, whose resources should be provided only for the care of the body, which means that the long term , but the results show that there is a high risk of death and rapid aging in this group.
Such observation is explained by pre-existing risk factors that adversely affect reproduction.These same factors can accelerate aging and increase the risk of death in those women.However, in this study, the association between increased mortality risk and accelerated aging among childless women remained significant even after adjusting for risk factors, such that pre-existing risk factors cannot fully explain the effect on both life expectancy and "birth history itself may have a direct effect on survival. Breastfeeding for certain diseases, as well as lack of social support from children.
The longest-lived women had an average of 2-2.4 children, gave birth at about age 27, had their first and last birth at age 24 and a half, and nearly 30.However, differences in survival and aging profiles between classes are modest, suggesting that "timing of reproduction and number of offspring may affect survival less than we think."
The researchers emphasize that these results are based on this particular sample and are not only driven by biological parameters, but also by socio-economic and cultural influences.Although they support the idea of balancing resources between offspring and body maintenance, this study can only show correlations, not causal effects.In addition, the researchers caution that they are not suggesting any individual-level fertility selection, as this study focuses on population-level observations."Therefore, a woman should not change her plans or desires for children based on this knowledge," he said.
[1] Hukkanen, M., Kankanpa, A., Heikkinen, A., Kaprio, J., Christopheri, R., and Oikainen, M. (2026). Epigenetic aging and reproductive history in a Finnish twin cohort.Nature Communications, 17(1), 44.
[2] Long, E. and Zhang, J. (2023).Evidence for the role of selection for reproductively advantageous alleles in human aging.Advances in science, 9(49), eadh4990.
[3] Wang, X., Byars, S. G., and Stearns, S. C. (2013).Genetic associations between postreproductive and family size in Framingham.Evolution, Medicine and Public Health, 2013(1), 241–253.
[4] Grundy, E., & Tomassini, C. (2005).Fertility history and health in later life: a case study in England and Wales.Social Science and Medicine (1982), 61(1), 217–228.
[5] Keenan, K., & Grundy, E. (2018).Reproductive History and Changes in Physical and Mental Health in European Adults.European Journal of Demography = Revue europeenne de demographie, 35 (3), 459-485.
