Freeze the eggs!
This post was initially submitted, unsuccessfully, to the Financial Times Opinion page.
Global birth rates are falling at an accelerated pace. According to the UN, the global total fertility rate (TFR) dropped to a record low of 2.25 in 2023 and is projected to have fallen further in 2024, to 2.2. At this pace, the TFR is set to dip below the replacement level of 2.1 nearly two decades earlier than the UN’s latest forecasts had anticipated.
The long-run decline in fertility has two main components. The first is the "quantum effect"—the trend for families to have fewer children as incomes rise, choosing instead to invest more in each child, particularly through education. Economics and evolutionary theory both rely on this shift in the quantity-quality trade-off to explain why fertility has fallen since the Industrial Revolution, even as wealth has grown.
The second component is the "tempo effect"—birth postponement. Women are delaying motherhood due to rising labour force participation and career opportunities—which increase the opportunity cost of having children—and shifting social norms. Other contributors include difficulty in finding a partner, precarious housing and job markets, and evolving personal preferences. Outright childlessness is increasing too, which neither the quantum nor tempo frameworks fully explain.
Countries seeing the sharpest fertility declines—Japan, South Korea, much of Europe and the US—are all marked by rising tempo effects. The average age of women at the birth of their first child (MAC) continues to rise: in Western Europe, MAC rose to 31.5 in 2023, from 28.0 in 1990. In the US, it climbed from 26.5 to just under 30 over the same period. East Asia shows similar trends. While tempo effects depress period fertility rates, they need not affect cohort fertility—if births are simply delayed, not foregone. In reality, however, the longer the delay, the greater the risk that intended births never happen. Life gets in the way.
Biology is unforgiving too. Female fecundity begins to decline in the early 30s and falls sharply after 35. If we plotted the economically optimal time to have children and the biologically optimal time on the same chart, the lines would diverge from the outset, until the latter hits zero at the onset of menopause.
Governments are spending billions trying to reverse falling birth rates, with limited success. Generous parental leave, childcare subsidies, and tax incentives all help, but they don't resolve the underlying tension between delayed childbearing and declining fecundity over time.
Technology can help. IVF offers one route for those facing involuntary infertility, but its success rates drop sharply with age. One underused tool in the assisted reproduction toolkit, meanwhile, is egg freezing. Unlike IVF, egg freezing allows women to preserve their eggs when they are biologically optimal—typically in their 20s or early 30s—for use later when the time is right. Egg freezing is safe and relatively non-invasive, but costly. In the UK, one round costs £5,000–£10,000, plus annual storage fees. Usage is increasing, but many women freeze their eggs too late. Data from the Human Fertilisation and Embryology Authority show that in 2019, 65% of women who froze their eggs were over 35, when egg quality is already in decline. Cost is likely a major factor.
This is where policy should help. If women face strong economic incentives to delay childbearing, governments should support that choice. Publicly funded egg freezing for women in their 20s could become a pillar of a modern pro-natal policy. Such a scheme would not replace existing family support measures, but complement them. By giving women an option to preserve fertility earlier in life, it directly addresses the biological limits of delayed motherhood. It could mitigate the long-run impact of tempo effects bleeding into cohort fertility, helping to stabilise overall fertility over time.
Not all women will want to freeze their eggs, and success rates will vary. But in an era where birth postponement is structurally embedded in women's fertility decisions, government support for egg freezing would give women—and society—a better shot at the families they want, when they're ready.