Working women who want to minimise career income losses related to motherhood should wait until they are about 30 years old to have their first child, suggests new research from Washington University in St. Louis.
For both college graduates and those without a college degree, the researchers found lower lifetime incomes for women who gave birth for the first time at age 30 or younger.
The hit was particularly stark for women without college degrees who had their first child before age 25.
The researchers studied data of 1.6 million Danish women aged 25-60 from 1995 to 2009, to estimate how a woman's lifetime earnings are influenced by her age at the first child's birth. Denmark collects data on 100% of its population.
"Children do not kill careers, but the earlier children arrive the more their mother's income suffers," said study co-author Raul Santaeulalia-Llopis, an assistant professor of economics in Arts & Sciences at Washington University.
"Our main result is that mothers lose between 2 and 2.5 years of their labour income if they have their first children before the age of 25."
Other findings include:
- College-educated women who had children before age 25 lose about two full years of average annual salary over their careers; women with no college degree lose even more, forgoing about 2.5 years of average annual salary during their working careers.
- Women who first give birth before age 28, regardless of college education, consistently earn less throughout their careers than similarly educated women with no children.
- College-educated women who delay having their first children until after age 31 earn more over their entire careers than women with no children.
- Noncollege-educated women who give birth after age 28 experience a short-term loss in income but eventually catch up with the lifetime earnings of women who have no children. Those who delay their first children until age 37 add about a half year of salary to lifetime earnings.