What’s the best age to have a baby?

By Samantha Weinberg

Babies are expensive – for women more than for men. The combination of maternity leave and childcare responsibilities, the burden of which, fairly or not, tends to fall on the mother, makes the career ladder dangerously greasy. A study by the Institute for Fiscal Studies showed that while the difference in wages between men and women was a mere crack in their 20s, it widened to a chasm in their 30s. Twelve years after their first child was born, British women are paid on average 33% less than men of the same age.

But while women may feel powerless to change childcare policy and entrenched social norms, they might be able to boost their earnings by waiting to conceive until they are more established in their careers. A study published in 2016 based on data from Denmark found that although all mothers experienced a short-term loss in earnings when they had a child, women who were 31 or older when they had their first baby had a higher lifetime income than women who had a baby before the age of 31. In fact, the study concluded that women who waited until 31 to have a child earned more over their entire careers than women without children.

The study’s authors suggest that older women, who tend to be more highly skilled, are harder to replace in the workplace – so companies may bend over backwards to support them. Older women may also be more attached to their careers, and less willing to give them up. And they tend to earn more so are better placed financially to offload their children on other people during the day.

Yet according to this study, there’s not much to be gained financially from delaying having children until after the age of 34. College-educated women who have their first child between the ages of 31 and 34 earn on average 13% more than women without children. However, women who have their first child between the ages of 34 and 37 earn only 2% more than women without children.

So, setting aside a couple of caveats – the researchers looked only at women with one child, and Denmark has generous childcare policies – the study implies that the best time, career-wise, to have your first child is between the ages of 31 and 34. Having a child before the age of 25 is particularly impoverishing: the study found that it reduces lifetime income by two years’ worth of earnings. The reason, the researchers suggest, is that people’s earnings these days are determined largely by their human capital, which accumulates at a higher rate when people are younger. So taking time off work in your 20s will have a bigger impact on earnings than taking time off in your 30s. That chimes with the researchers’ finding that college-educated women suffer the biggest disadvantage: they have the highest potential earnings, so their incomes are hit hardest by taking time off to have a baby in their 20s.

Given that female fertility is already declining by the age of 30 and the risk of conceiving a child with Down’s syndrome is rising, 31-34 seems the optimal age for a woman to produce her first child. But she should also consider the age of her partner. A recent study by Harvard Medical School found that there was a 62% drop in sperm supply between men in their early 30s and those in their early 40s, making conception harder. The reasons for the drop are not yet known, but it does suggest the pulling power of sugar daddies may be on the wane.

ILLUSTRATION JAMIE EDLER