The researchers examined whether men or women have fewer children and show that demographic imbalances around the world – in particular, a growing share of men – are affecting men’s fertility.

– Globally, women now have higher fertility than men – and this trend looks set to continue, says Vegard Fykse Skirbekk.

The research team, which also includes researchers from the Max Planck Institute for Demographic Research and the UN Population Division, has investigated developments and future trends in gender differences in fertility, for example in the overall global fertility rate.

They analysed how imbalances in population composition affect men’s fertility, drawing on information from the UN report World Population Prospects and using statistical methods.

– Our main findings point to a historical turning point, from higher fertility among men to higher fertility among women. This shift occurred globally in 2024. The change is driven by an increase in the proportion of men in the population, explains Skirbekk.

The study he led was recently published in the respected journal PNAS.

There, the researchers highlight long-term global trends, including rising numbers of sex-selective abortions in some countries – where girls are not carried to term – lower mortality among men, and the fact that significantly more boys than girls are now being born each year.

– Historically, the surplus of men tended to disappear before they reached reproductive age. That is no longer the case, elaborates Skirbekk.

The study also shows that the shift from higher fertility among men to higher fertility among women has occurred at different times around the world and is linked to demographic developments.

In Oceania, South America and Asia, this transition has only taken place recently. In sub-Saharan Africa, it is unlikely that we will see a shift from higher male fertility to higher female fertility before 2100, as the decline in fertility has now stalled while mortality remains high, according to the researchers.

In most European and North American countries, this change took place several decades ago, in the 1960s and 1970s – and more recently in Latin American countries.

Low fertility among men is increasing as a result of the growing share of men in the population. Skirbekk points to some societal challenges this may bring.

– The challenges particularly affect men who remain childless – a situation often associated with poorer health and increased dependence on professional care in old age, he stresses, adding:

– Political solutions are needed to counteract gender differences in fertility and their consequences, such as childlessness among men.

The researchers therefore propose three concrete measures to mitigate the social consequences of this development:

• Strengthen women’s position in society, among other things to counteract sex-selective abortions
• Invest in education and create jobs that give childless and single men the opportunity for a stable career, thereby reducing their vulnerability to organised crime
• Provide social opportunities for single and childless men – for example, friendship circles and networks – as well as legalising assisted reproduction and similar technological solutions

– If the challenges facing these men are not taken seriously, we risk a setback for gender equality and increased social conflict, warns Skirbekk.

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