The chances of not having children are much higher for people who suffer from certain diseases during their youth, an international team of researchers has found, examining the link between 414 early-onset diseases and childlessness over the years. of life in more than 2.5 million people born in Finland and Sweden. Their findings have been published in Nature Human Behavior.
In many countries in Western Europe and East Asia, 15% to 20% of people born around 1970 do not have children. Although numerous social, economic and individual preferences have been studied, little research has examined the influence of different diseases on the lack of offspring, especially those diseases that manifest before the maximum reproductive age.
“Several factors are driving an increase in childlessness around the world, and postponing parenthood is a major factor potentially increasing the risk of involuntary childlessness. “Our study is the first to systematically explore how multiple early diseases are related to lifetime childlessness and low parity in both men and women,” said Dr. Aoxing Liu, lead author of the study. and postdoctoral researcher at the Institute of Molecular Medicine at the University of Helsinki in Finland (FIMM).
Mental disorders make motherhood and fatherhood difficult
The researchers analyzed data on 414 early-life disease diagnoses from 1.4 million women born between 1956 and 1973 and 1.1 million men born between 1956 and 1968. All were alive at age 16. years, they did not emigrate, and most of them had finished their reproductive stage at the end of 2018 (defined as 45 years for women and 50 years for men).
The main analyzes of the study focused on 71,524 pairs of full sisters and 77,622 pairs of full brothers who showed differences in their childless status. Interestingly, the association between illness and childlessness was more similar between people without children and their siblings who had only one child, compared to those with more children.
Of the 74 illnesses significantly associated with childlessness in at least one sex, including 33 shared between women and men, more than half were mental and behavioral disorders. Additionally, several novel associations were discovered between diseases and childlessness, such as autoimmune and inflammatory diseases. A full list of results can be found in this interactive dashboard.
A quarter of the 1.1 million men studied did not have children, compared to 16.6% of the 1.4 million women. People with lower educational attainment in Finland and Sweden were more likely to be childless compared to the general population, and whether an individual was childless was notably related to her parents’ age and her level of education. .
Of the 74 illnesses significantly associated with childlessness, more than half were mental and behavioral disorders
The researchers also found significant gender differences in the relationships between illness and childlessness. For example, schizophrenia and acute alcohol poisoning showed stronger associations with childlessness in men, while diabetes-related diseases and congenital anomalies showed stronger associations among women.
Sex differences were notable in age of disease onset, with stronger associations earlier for women diagnosed between ages 21 and 25, and later for men diagnosed between ages 26 and 30. For example, women diagnosed with obesity experienced higher levels of childlessness if they received their initial diagnosis between ages 16 and 20, compared to those diagnosed at an older age.
Professor Melinda Mills, lead author and director of the Leverhulme Center for Demographic Sciences at the University of Oxford, said: “As well as reinforcing demographic research into assortative mating and other socio-economic factors linked to childlessness, this paper underlines the need of interdisciplinary research and greater emphasis on public health to address early illness among men and women in relation to childlessness.”
The study also revealed that not having a partner was a relevant factor in the connection between illnesses and childlessness, representing approximately 29.3% in women and 37.9% in men. People without children were twice as likely to be single, while six diseases in women and 11 in men remained associated with childlessness among people in a relationship.
Associate Professor Andrea Ganna, another of the lead authors and leader of the FIMM-EMBL group at the FIMM of the University of Helsinki concludes: “This study reveals a connection between early illness and childlessness, which differently influences both in women as well as in single men and couples. By assessing the role of multiple early illnesses in childlessness among 2.5 million people in Finland and Sweden, this study paves the way for a better understanding of how illnesses contribute to involuntary childlessness and the need to improve public health interventions.
