Researchers analyzed two centuries of birth data—one trend stood out

Researchers analyzing more than 200 years of data from 237 countries have uncovered a surprisingly consistent pattern behind declining birth rates worldwide.

Their analysis of records spanning 1800 to 2020 found that nations tend to follow one of two common pathways as fertility falls and life expectancy rises, regardless of differences in culture, politics or geography.

The findings, published in the journal Evolutionary Human Sciences, suggest that demographic transition—the shift from high birth and death rates to lower ones—may be governed by universal mechanisms rather than country-specific circumstances.

Demographic transition has long been associated with modernization. As countries develop, mortality rates typically decline first, followed by a drop in fertility.

The new study also points to education as a potentially important factor. Kenji Itao, a researcher at the RIKEN Center for Brain Science in Japan, told Newsweek that in highly competitive educational environments, parents may feel pressured to devote increasing amounts of time and money to each child.

“Reducing the financial burden of education on households is required to recover fertility in the education-intensive Phase II,” he said.

He explained that resources that might otherwise make having a second child feasible can instead be directed toward greater investment in a first child, including private tutoring and other educational expenses.

While several governments are searching for ways to reverse falling birth rates, Itao cautioned that his research did not directly evaluate the effectiveness of specific policies.

However, he pointed to recent efforts in China and South Korea aimed at curbing intense educational competition and reducing reliance on private tutoring.

“It will be important to monitor whether these policies reduce household educational expenditure and recover fertility,” he said. “At present, however, it is too early to regard them as proven fertility policies.”

Yet whether the same underlying processes operate across the globe has remained an open question.

To investigate, the study examined the relationship between crude birth rates and life expectancy at birth across more than 200 years of global demographic data. The analysis revealed two dominant phases that appear repeatedly across countries.

The first phase, which prevailed until around the mid-20th century, was characterized by high child mortality and steady population growth.

During this period, countries tended to follow a pattern in which fertility and life expectancy changed together while maintaining a relatively stable relationship.

The second phase emerged after about 1950 and has become the dominant pathway worldwide.

It is marked by low child mortality, increasing life expectancy and continued economic development, alongside falling birth rates.

According to the researchers, most countries either follow one of these pathways or transition from the first to the second as they develop.

To explain the observed patterns, the researchers developed a theoretical model based on a trade-off between the number of children families have and the amount they invest in each child’s education.

As education becomes more important for economic success, parents may choose to have fewer children while investing more resources in each one.

The model suggests that several factors can accelerate the shift to the second phase, including lower educational costs, greater social mobility and cultural influences associated with modernization and Westernization.

Itao stressed that the study should not be interpreted as an argument against education itself.

“Mass public education is one of the great achievements of modernization, and a well-educated population is essential for the innovation that can help societies adapt to aging populations and smaller workforces,” he said.

“Providing affordable, high-quality public education to a broad population may allow societies to maintain the benefits of educational investment while reducing one of the pressures that discourages parents from having additional children.”

Reference

Itao K. Two universal pathways in demographic transition. Evolutionary Human Sciences. 2026;8:e28. doi:10.1017/ehs.2026.10054

Contact Newsweek editors on this story: Kara Dolman and Emma Lee-Sang