If we look at how many years of experience men and women have at different ages, we see a clear pattern.
Until about age 30, men and women of the same age have the same median number of years of experience. This suggests that men and women in their teens and twenties are equally likely to be working and gaining experience, or taking time out to do something else.
But female respondents in their 30s have fewer years of experience than men of the same age. The median (middle) man at age 31-35 has 5 more years of experience than men 5 years younger. But the median woman at age 31-35 only has 2 years more than women 5 years younger. In other words, starting in their thirties, women are taking time out of work to do other things, such as raising children.
That experience gap remains among older women, and doesn't get significantly wider except among the oldest workers, who hail from a generation ruled by different norms and attitudes.
Since this is not a longitudinal study, we can't separate out these kinds of generational effects, but the need for women to take at least some time for childbirth and nursing is likely to stay with us.