Researchers from Washington University in St. Louis say they've done the first study that compares women's ages when they have their first baby to their total income from ages 25 to 60, and it looks like waiting until your 30s makes a difference.
For a study published in the journal PLOS ONE, they looked at data from 1.6 million Danish women, including birth statistics and work experience, and calculated their average salaries. (Denmark collects socioeconomic and health data for its entire population.) Next, they estimated income losses for women in multiple segments: those who had their first child before 25, in three-year age groups until 40, and women 40 and up.
They found that women who give birth before 25 lost between 2 and 2.5 years of income over their lifetimes — the higher number is if they didn't have a college degree. Regardless of education level, having a baby before age 28 meant earning less throughout their careers than women who didn't have kids. But women who went to college and had a kid at 31 or older actually earned more than childless women.
As the study's co-author said in a release: "The earlier children arrive the more their mother's income suffers. There is a clear incentive for delaying." They observed that more and more college-educated women are waiting to have their first kid between 28 and 34, presumably when they're more established in their careers.
And reminder: This income disparity was observed in a country that offers paid parental leave. Mothers get 4 weeks at the end of their pregnancy plus 14 weeks after the birth of the child, and then parents have an additional 32 weeks to share between them. The authors believe the effects would be even more pronounced in the United States, where we still do not have nationwide paid leave. Plus, the wage gap between women who do and don't go to college is greater in the U.S. than in Denmark, they said.
The authors argue that women making less money than they could simply because of pregnancy timing is a loss for society (hello, taxes) and call on employers to cover fertility benefits. One step at a time: Let's get that paid family leave first.