A growing “relationship recession”, alongside economic insecurity, delayed parenthood and changing attitudes towards having children, is contributing to an unprecedented fall in fertility rates around the world, according to a major new study.
The research - published in the ‘Reproductive BioMedicine Online’ journal - and led by demographer and deputy director of the Vienna Institute of Demography, Tomáš Sobotka, warns that the latest global decline in births is “more widespread, deeper and more permanent than previously anticipated”.
It found that more than one in four people worldwide – over 2 billion people - now reside in countries where the fertility rate is lower than 1.3 children per woman.
Without significant levels of immigration, fertility at that level would eventually result in “rapidly shrinking populations”.
Meanwhile, countries with fertility rates of 2.1 children per woman or lower are now home to over half the world’s population.
Examining what he calls a “global fertility freefall”, Sobotka argues that no single factor can explain the trend.
Instead, falling birth rates appear to be the result of a combination of economic, cultural and social changes affecting everything from employment and housing to relationships, contraception and attitudes towards parenthood.
The Iona Institute, commenting on the research, highlighted the “decline of marriage and intimate relationships” as an especially important part of the picture.
An increasing share of adults in their 20s, 30s and even 40s are neither married nor in romantic relationships, reducing the number of people entering the stable partnerships in which most children are born.
Attitudes towards parenthood are changing too. Young adults are also increasingly unsure about whether parenthood is something they want for themselves, while deliberately remaining childless has become more socially accepted.
Sobotka says fertility intentions among younger generations are also “lower and more fluid”, weakening the traditional two-child family norm.
Another major factor is the increasing postponement of parenthood.
People are marrying and having children later than in previous decades, often because they spend longer in education, struggle to secure stable employment, or cannot afford suitable housing.
However, postponement can itself reduce eventual family size because biological fertility declines with age.
The study notes that assisted reproductive technologies cannot fully compensate for years of delayed childbearing.
Ireland illustrates several of these trends. Its fertility rate stood at 1.5 children per woman in 2024, down from 1.98 in 2004 and from a brief return to replacement levels in 2009.
The country, once known for having some of the largest families in Europe, now has a fertility rate only slightly above the European average.
Marriage has also declined. The number of marriages fell from 5.2 per 1,000 adults in 2004 to 3.8 in 2024, excluding the exceptional Covid years.
Irish women are also among the oldest first-time mothers in Europe. The average age of a woman having her first child reached 33 in 2023, while Ireland recorded Europe’s highest proportion of mothers aged over 40.
Though the research suggests that economic insecurity remains an important explanation for such changes, Sobotka cautions against treating it as the whole answer.
Birth rates have often remained low even after economies recovered from recessions and unemployment fell, suggesting that deeper changes in relationships, expectations and lifestyles are also at work.
Housing can have similarly complex effects. High rents and unaffordable property may prevent younger adults from establishing independent households or starting families, while rising house prices can sometimes increase fertility among existing homeowners by giving them a greater sense of financial security.
Concern about the future is another factor, as are anxieties around inequality, war, climate change and political instability. These are all contributing to a wider pessimism among younger adults about whether their children would have better prospects than they did.
An analysis referenced in the research describes a “crushing sense that the future is too uncertain” for some young people contemplating the long-term responsibilities of parenthood.
Gender relations within the home may also affect decisions about marriage and children.
Where women participate equally in education and paid employment but continue to shoulder a disproportionate share of housework and childcare, family life can become less appealing, particularly to highly educated women, the study argues.
Technology may be adding another dimension.
Sobotka points to research associating growing internet use with declining in-person social interaction and a reduction in romantic relationships, while suggesting that future advances in AI could bring further changes to employment, relationships and family life.
A recent US study examining the rollout of smartphones has added to that debate.
Economists Caitlin K Myers and Ezekiel Hooper estimated that early access to the iPhone could account for between 33% and 52% of the decline in the general US fertility rate between 2007 and 2011.
They did not claim smartphones directly reduced biological fertility but suggested that the technology may have changed behaviour by reducing in-person socialising and sexual activity while widening access to information around contraception and reproductive health.
The authors argued that if fewer relationships are forming in the first place, conventional government attempts to increase births through cash incentives and childcare subsidies may address only part of the problem.
Other research nevertheless suggests that many young people still want marriage and children.
A recent international survey by the UN of people aged 18 to 39 found that 70% wanted to marry, while only 16% said they preferred to remain single.
Among those who wanted a long-term relationship, around one in four were nevertheless single and not dating.
More than half (57%) identified economic insecurity or housing as barriers to forming a lasting relationship.
A similar gap emerged between desired and actual family size. Respondents said they ideally wanted around two children on average, but the number of children they actually expected to have was consistently lower.
Even among childless adults aged 35 to 39, 79% of men and 72% of women still wanted children.
Housing and financial insecurity were cited by 72% as obstacles, alongside difficulties finding a suitable partner and health concerns.
Sobotka’s study is doubtful that governments will be able to reverse the trend through straightforward pronatalist policies.
Financial support for parents may have some effect, but cannot by itself create stable employment, affordable homes, stronger relationships or suitable partners.
Nor can public policy easily reverse changing attitudes towards parenthood or uncertainty among young adults over whether they want children.
The study concludes that the present fertility decline is “qualitatively different from the past fertility declines”, which were often temporary and followed economic crises or periods when couples simply postponed having children, he said.
Today’s decline is taking place across a much wider range of countries and is being shaped by several long-term trends at once, he observed.
