A new study published in the Journal of Marriage and Family suggests that although highly educated, dual-career couples both think their workloads increase equally when they have their first child, that isn't the case.

When asked by researchers at The Ohio State University, both men and women said they believe their workload increased by four hours a day after their child was born, according to PsyPost, but detailed time diaries told a different tale - the women's workload increased by two hours while the men's workload only increased by 40 minutes.

"Women ended up shouldering a lot more of the work that comes with a new baby, even though both men and women thought they added the same amount of additional work," said Claire Kamp Dush, co-author of the study and associate professor of human sciences at OSU, according to PsyPost.

"The birth of the child dramatically changed the division of labor in these couples," said Jill Yavorsky, co-author of the study and doctoral student in sociology at Ohio State, according to PsyPost. "What was once a relatively even division of household work no longer looked that way."

"These are the couples you would expect to have the most egalitarian relationships," Kamp Dush said, according to PsyPost. "They have the education, the financial resources and the other factors that researchers have believed would lead to equal sharing of responsibilities. But that's not what we found."

The couples were studies again when the baby was about 9-months-old. Men and women tended to backslide into more traditional gender roles without even noticing. "Nine months after the baby arrived, couples continued to report putting in the same hours of work, but their diaries revealed that in fact 'women added 22 hours of childcare (physical and engagement) to their work week while doing the same amount of housework and paid work as before. Men added 14 hours of childcare to their work week, but did 5 fewer hours of housework after the baby's birth,'" according to the Council on Contemporary Families.

The "fun" part of having a baby - the "child engagement" like reading and playing - showed a smaller gap between genders with men spending four hours per week in child engagement and women spending six hours. Cutting back on working outside the home doesn't account for the extra hours women are putting in. "A lot of data shows that many women eventually decrease their time spent at paid work after having children, but we don't know when it happens," Yavorsky said, according to PsyPost. "This study shows that they're not doing it right after the birth of their first child."