Their employment rate is also slightly lower than women in their early 20s.
"This smaller share reflects the fact that, within marriages, mothers are still more likely than fathers to specialize in child care," the Fed noted.
Today, 26% of mothers are stay-at-home parents, compared with just 7% of fathers, according to a separate Pew study from August.
Mothers working full time and year-round outside the home rarely recoup the lost wages, which add up to $20,000 a year, on average.
Working moms are making just 71 cents for every dollar paid to fathers, according to an analysis of Census data by the National Women's Law Center.
Persons:
Kelly Shue
Organizations:
Federal Reserve, Pew Research Center, Yale School of Management, CNBC's, National Women's Law