Washington ? The number of working moms who are the sole breadwinners in their families rose last year to an all-time high, and the number of stay-at-home dads edged higher, in a shift of traditional gender roles caused partly by massive job losses.

The number of moms who were the only working spouse rose for the third straight year, according to Census Bureau figures released Friday. The number of dads who were the only working spouse dropped, and the number of stay-at-home dads ticked higher.

The figures are for married couples with kids under 18.