Most parents at some point have probably thought their children have taken years off their lives, but the opposite is true. Parenthood is associated with increased life expectancy. A new study exploring this effect attributes it to the care offered by children as their parents age.
Deep in sleep denial, new parents might sympathize with the old joke that they don't really live longer, it just feels like it, but the numbers prove otherwise. Many studies have confirmed that parents do actually have longer lives, on average, than adults who never procreate, but have not been able to explain why.
Dr Karin Modig of the Karolinska Institute in Sweden set out to answer this question, at least for Swedes. Using Sweden's extensive population databases she looked at years of death for people born between 1911 and 1925, finding that a man with at least one child, upon reaching the age of 60, could expect to live two years longer than a childless contemporary. For women, the difference was 1.5 years. With a sample size of more than 1.4 million people, the figures are robust.
Modig reported in the Journal of Epidemiology and Community Health that, after controlling for education level, the mortality gap rose with age. For example, a 70-year-old Swedish man born during Modig's study period had a 3.3 percent chance of dying before reaching 71 if he was childless, but just 2.9 percent with at least one child. By 90, the figures were 17.7 and 16.2.
The difference was about twice as large among unmarried men (including widowers and divorcees) as married men.
Modig attributes the difference to the support children provide to aged parents struggling to cope with the changes age brings. This is not just in the form of direct care, but also assistance in navigating the bureaucracies such as the health care system and finding appropriate living places.
Many other theories have previously been raised to explain parents' longer life expectancy. Having children reduces the risk of certain cancers in women, and might provide additional unknown benefits. Alternatively, it is possible that parents are, on average, healthier in ways that existing measurements don't pick up. However, the Swedish data didn't support a wide range of such theories, at least as the major factor.
The idea that children help keep frailer parents alive by ensuring they get the support and medical attention they need is highly consistent with Modig's observations, with the greatest differences in mortality rates being seen among the oldest individuals. Most alternative hypotheses predict the difference in mortality should decline with age, in contradiction to what Modig found.
Contrary to some previous claims, the gender of the children had little effect in this sample.