Fertility rates began falling in most of the world starting in the last century. By the 1970s, the U.S. had dipped under the replacement rate of 2.1 children per woman, a trend that has continued on a declining slope.

In her new working paper, “The Downside of Fertility,” Claudia Goldin, the Henry Lee Professor of Economics, takes a deeper dive into the cultural changes around gender that are driving down fertility rates.

The economic historian and 2023 Nobel laureate introduced a model in a previous publication that links low fertility rates to higher levels of friction between the sides around gender and generation. This paper, she said, tackles a seeming contradiction in the data.

Across the 18th and 19th centuries increases in the birth rate were seen during periods of prosperity or at the end of economic downturns, as evidenced by the post-World War II baby boom. However, since the later part of the 20th century, that link no longer holds true.

“One of the great demographic surprises” of this time, Goldin writes, “has been the negative relationship between per capita income levels and fertility.”

Although fertility rates fell earlier and faster in developed countries, defined by Goldin as members of the Organisation for Economic Co-operation and Development, they have now gone down even in sub-Saharan Africa.

“When you look at what these birth rates were for just the previous generation, it’s astronomical change.”

“The fertility decline is just about everywhere,” said Goldin, who is also the Lee and Ezpeleta Professor of Arts and Sciences.

The wealthier Middle Eastern countries had birth rates around six or seven children per woman, but the United Arab Emirates “has a birth rate now that is lower or about the same as baby-scarce Japan,” dipping “to about 1.2,” Goldin said, while the birth rate in Saudi Arabia is 2.3.

“When you look at what these birth rates were for just the previous generation, it’s astronomical change,” she said.

The global shift, she continued, can be traced to one common cause: the increased agency of women, who during the last century became increasingly able to opt out of traditional family roles to pursue other options, such as education and careers.

“Wherever you get increased agency, you get reduction in the birth rate,” said Goldin. “The central cause arises when women have autonomy and have the ability to be educated, to have occupations and careers.”

This can lead to conflict with men, who are more comfortable with traditional roles. “Men don’t want to give up what they had in the past,” Goldin said.

Goldin’s close read on the historical patterns revealed fascinating subtleties.

Fertility rates were declining at a slower pace in the U.S. until the onset of the “Great Recession” in 2007. In Northern Europe, rates started declining faster in 2010.

However, the decreases were “substantial” among college graduates, who delayed or avoided having children despite, on average, enjoying higher earnings. This avoidance is “testament to the mismatch factors” that Goldin has brought to light in previous work.

In other words, men want to start families, but they don’t face the same obstacles combining employment and parenthood. And women, by and large, want time for both work and children.

By now, birth rates have been in decline, at least in rich nations, for 50 years. So Goldin can’t help but wonder: “Why are we talking about this now?”

She referred to the current, often-heated public discourse around ways to increase birth rates in the U.S. Until we, as a society, address the real underlying causes, Goldin said, “you really can’t address what policies can address the declining fertility rate.”

And the issues, she notes, are not just a concern of the left but bridge the political divide.

“One of the things that is important to know is that traditional women today, evangelical women today still want respect in the workplace,” she said. “They still want to know that they’re being promoted appropriately, that they’re being paid the correct amount. It’s not as if women are eschewing all of the rights that they have gained over time.”

The issue of falling birth rates underlies everything, argued Goldin, who is currently working on a book about women’s rights.

“I’ve written on various aspects of demography,” she said. “About the first declines in infant and child mortality in America and the role of public health and the cleaning up of the nation’s water supply and the separation of the sewage from clean water. I’ve written about why women live longer than men and whether that’s always been the case.” (The answer is no.)

“The issues concerning the change in population, about families and children, are absolutely fundamental to everything that I do,” concluded Goldin. “I can’t talk about the labor force unless I talk about population.”