Obviously nobody is forcing women to stay at home at the point of a gun. However, I think it can't be discounted the degree to which women are pressured socially to take on primary caregiver roles.
My wife and I (~30, educated professionals) have a 8-month old. My wife as zero interest in staying at home. But from the minute she got pregnant the pressure started. My mom and her mom (both of whom work/ed) suggested that may she should stay at home for a few years when the baby was young. She's constantly bombarded by parenting fads that tell her she's a bad mom if she doesn't breastfeed/wear her baby around in a sling/etc. Those fads are never very compatible with professional working life.
Meanwhile, nobody has any expectations of me. Nobody wonders why I don't take a few years off to raise the kid. None of the parenting fads are aimed at me. Heck, my own mother gets nervous whenever I have responsibility for the kid.