Research involving Pompeu Fabra University studies the relationship between having or not having a romantic partner with changes in fertility desires in Japan. The study, which involved Ryohei Mogi , a researcher at the University's Department of Political and Social Sciences , together with Ryota Mugiyama (Gakushuin University, Japan) and Alyce Raybould (University College London, UK), shows that people without a romantic partner are more likely to revise their fertility desires downwards, especially from "wanting children" to "unsure". These findings underscore the importance of romantic relationships in shaping fertility desires and highlight that many people may remain unintentionally childless.
In Japan, nearly 70% of unmarried people are not in a romantic relationship
Japan has the world's highest percentage of childless individuals, cohabitation is not widespread, and nearly 70% of unmarried people are not in a romantic relationship. Furthermore, nearly all childbearing happens within married partnerships. These conditions make the Asian country a particularly interesting context for examining the links between romantic relationship and fertility desires, with broader implications for understanding the country's low fertility rate.
Not having a partner lowers fertility desires
The study uses data from the Japanese Life Course Panel Survey (JLPS), conducted between 2009 and 2023, focusing on men and women aged 20-49 who have never had children. Relationship status was classified into four groups: "married", "cohabiting", "in a relationship but not cohabiting", and "not in a relationship". Fertility desires were assessed using three categories: "want children", "unsure", and "do not want children". Applying a fixed-effects model, a statistical method that tracks the same individuals over time, the researchers examined how changes in relationship status influenced changes in fertility desires.
The results revealed that among childless people, those who do not have a partner are more likely than those who are married, cohabiting, or in a relationship to shift their fertility desires from "wanting children" to "unsure" or "not wanting children". The change from "wanting" to "unsure" was especially pronounced. Crucially, this shift appeared soon after individuals became unpartnered, rather than growing steadily with longer periods of non-partnership.
Among those who remained single throughout the survey period, 28% of women and 21% of men consistently expressed a desire to have children, whereas only 10% of women and 7% of men consistently reported not wanting children.
According to the authors: "The study reveals how the presence or absence of a romantic partner affects changes in fertility desires, and that not having a partner increases the uncertainty surrounding people's desire to have children. At the same time, many people without children still wish to become parents."
Towards More Nuanced Support Strategies
These findings provide valuable insight into the psychological and social barriers that single people may face in realising their fertility desires. They suggest that romantic relationships function as a key life event in the formation of the desire to have children.
For policymakers, the results highlight the need for more nuanced support strategies. Instead of treating "unmarried individuals" as a homogeneous group, it is important to recognise the differences between those in a relationship and those who are not. In particular, it is crucial to better understand dating behaviour itself. Many individuals without partners still express a clear desire to have children, yet remain unpartnered. Analysing why people with fertility desires do not have partners—whether due to economic insecurity, work–life balance issues, or limited opportunities for social interaction—can provide valuable insight into the social barriers they face. If such factors are more systematically studied and reflected in policy, support measures could more effectively help individuals achieve their fertility desires.
Reference article: Mogi, R., Mugiyama, R. I Raybould, A. (August 2025) "Exposure to non-partnership and fertility desires among childless population in Japan". Social Forces
https://doi.org/10.1093/sf/soaf123
https://academic.oup.com/sf/advance-article-abstract/doi/10.1093/sf/soaf123/8222480
