Falling Fertility Rates Point to Economics, Not Biology

The fight over falling fertility rates just took a sharp turn: one new letter argues the real culprit is not failing human biology, but the way people now live, work, and form relationships.

Writing in response to recent coverage of research on pollutants and fertility, Peter Foreshaw Brookes says the global decline in fertility rates should not be read as evidence of rising biological infertility. His central point cuts against a growing narrative: reports about environmental harms may raise valid concerns, but they do not, in his view, explain the recent drop in births. Instead, he points to economic conditions and smartphone use, particularly their effect on coupling, as more plausible drivers.

The letter’s core challenge is simple: fewer births do not automatically mean people have become less biologically capable of having children.

Brookes backs that argument by pointing to recent evidence that complicates the infertility story. He says a meta-analysis published last year, which controlled for regional variation, found sperm counts rose in the US in recent years. He also highlights time to pregnancy, a measure that tracks how quickly couples conceive. In Britain, he notes, that measure increased in the late 20th century, but in the US it stayed broadly stable from 2002 to 2017 for women under 30, with only a small increase for women who already had a child. He adds that infertility in developed countries has remained roughly flat or even declined in recent years.

The argument lands in a wider debate that often blurs two separate questions: can people conceive, and do they choose to have children? Those are not the same issue. Costs of housing, childcare, and job insecurity can push family plans out of reach, while shifts in dating and partnership patterns can shrink the number of couples who even get to that decision point. Reports indicate Brookes wants readers to keep that distinction front and center before drawing sweeping conclusions from alarming fertility headlines.

What happens next matters because policy follows diagnosis. If biology drives the decline, governments and researchers may focus on pollutants and reproductive health. If economics and social change drive it, the answers look very different: affordability, stability, and the conditions that make family formation possible. The stakes reach well beyond one academic dispute, because how societies explain falling birth rates will shape how they try to reverse them.