These changes spawned a number of other products that catered to on-the-move parents who had kids in tow. The breast pump came onto the market at around the same time, as did more-advanced car seats. Gone were the stately and spacious prams that once transported babies around the neighborhood; instead, parents started wheeling their kids around in compact strollers or strapped their babies into a Snugli, a carrier that sits on parents’ chests and lets them carry their kids around as if in a kangaroo pouch. With a Snugli, parents could keep their infant physically close, even while walking around or running errands.

These innovations reflect a change in how parents spent time with their children, according to Paula Fass, a professor of history at the University of California, Berkeley and the author of The End of American Childhood. In the 1980s, parents were moving in two directions at once: They spent more time on leisure activities, but they also sought to maximize the time they spent with their kids. Parents, Fass says, wanted “the child to be able to fit comfortably into their new lifestyle. Instead of adapting to the child by staying at home, you have the child become part of the pattern.” Devices like the wall-mounted changing table and chest-strap infant carriers made on-the-go caregiving convenient.

This represented a departure from the way mothers used to plan their days. Fass says that mothers used to “literally [stay] at home with their children.” While they cooked or cleaned, mothers would put their kids in the playpen or let them play outdoors. In the 1980s, “Women not only went out to work, but they engaged in a whole lot of other activities that took them outside of the home, to which they felt comfortable—increasingly comfortable—bringing their children. And that’s true with fathers too.” In other words, there came to be more and more spaces where parents spent time with their children.

But even as diaper-changing stations have done a lot to help mothers operate more flexibly outside the home, they haven’t done much to alter the traditional division of child-rearing labor. A changing table is much likelier to be found in a women’s restroom than a men’s restroom. This imbalance keeps fathers from taking care of their children while out and about, and poses an everyday challenge to men in same-sex partnerships.

Changing tables’ absence from men’s rooms harkens to an earlier time, when fathers were usually responsible for fewer of the everyday tasks of parenting. Yet mothers and fathers have slowly moved toward parity in housework and childcare, and some surveys have suggested that young Americans increasingly expect parenthood to be an equally-divided endeavor. As one New York state senator who has advocated for equal access to changing tables wrote in 2015, “If we expect fathers to bear more of the burden of child-care, we must ensure that public accommodations reflect this new normal.”