Women Now Have Higher Fertility Rates Than Men for First Time in History

For most of recorded history, men have had higher fertility rates than women. That might sound impossible, since it takes one of each to make a baby. But the math behind fertility rates depends on dividing the number of births by the number of people of childbearing age in each sex. When one sex has fewer people in that age range, their rate goes up. For centuries, wars, higher male mortality, and the fact that men tend to die younger meant there were simply fewer men around, which pushed their fertility rate above women’s.

In 2024, that long-standing pattern quietly reversed. A study by researchers at the Max-Planck Institute for Demographic Research found that women now have higher fertility rates than men on a global scale, for the first time. And this is not a move toward equality between the sexes. It’s a growing gap heading in the opposite direction, driven by a surplus of men at childbearing ages that is pulling male fertility rates down.

Why the Fertility Rate Gap Flipped

The study, published in the Proceedings of the National Academy of Sciences, identifies several forces that converged to flip this pattern. Death rates have been declining around the world, and the gap between how often men and women die has been narrowing. As fewer young men die before reaching the age when they might have children, the male surplus at those ages grows. On top of that, in some countries, decades of sex-selective abortion, the practice of ending pregnancies based on the sex of the fetus, has produced generations with far more boys than girls.

These forces have created a growing surplus of men among people of childbearing age worldwide. More men competing for fewer women means the same number of births gets spread across a larger male population, dragging the male fertility rate down. Meanwhile, with fewer women in that age bracket, each birth contributes more to the female rate, pushing it higher.

The researchers used population data from the United Nations to estimate past, current, and future differences between male and female fertility rates around the world. Their analysis confirmed that the global crossover, the moment female fertility rates passed male fertility rates, happened in 2024.

Where the Gap Between Men and Women Is Widest

While the crossover is a worldwide event, it is far from even. The study finds that the gap is expected to grow most sharply in countries like China and India, where decades of sex-selective abortion have deepened population imbalances. In those nations, the difference between male and female fertility rates is projected to reach as much as 20 percent.

That number points to a deep structural imbalance, with large numbers of men facing serious barriers to partnership and parenthood. In a world where men and women existed in roughly equal numbers at childbearing ages, their fertility rates would be nearly identical, with small differences driven by things like age gaps between partners. A 20 percent gap signals a fundamental mismatch in the population.

A Problem With No Quick Fix

The study stands out not only for identifying the crossover but for showing that the trend has no signs of slowing down. The growing surplus of men at childbearing ages is expected to keep shaping fertility patterns for decades. The researchers describe this as a widening gap rather than a correction toward balance.

This matters for reasons well beyond individual family planning. Societies with large surpluses of unmarried young men have historically faced serious problems. Other researchers have linked surpluses of unmarried young men to higher rates of crime and sexually transmitted diseases, particularly in East Asian countries. The study itself sticks to the demographic picture rather than predicting specific social consequences. What the study’s authors do stress is that sex differences in fertility have been dramatically understudied. Most demographic research focuses on female fertility rates, often ignoring the male side entirely.

The surplus of men is not a problem that can be fixed quickly, even in countries that have taken steps to ban sex-selective abortion. Children born during periods of extreme imbalance are already growing up and entering their childbearing years. The demographic consequences of those imbalances are locked in for a generation.

For the billions of people living in the countries most affected by this shift, particularly across large parts of Asia, the growing gap between male and female fertility rates will shape personal lives and national policy alike. Beyond individual lives, the shift raises policy questions around elder care, social support for the childless, and the long-term stability of marriage markets, though those effects were not directly modeled in the study.

By tracing the reversal and its expected path forward, the study makes the case that male fertility, and the structural forces shaping it, deserves far more attention from researchers and policymakers than it currently receives. The historical assumption that men reproduce at higher rates than women is now officially outdated, and the reversal is only picking up speed.

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