Being a Working Mother Is Rather Traditional
You hear it all the time. Mothers are meant to be home with their children. Mothers aren't supposed to leave their babies with someone else and spend all day out in the workforce. Traditionally, women stay home and raise kids. This is often accompanied by some adage about indigenous cultures in the Global South (usually inaccurate and always offensive) or how prehistoric moms raised their cave babies, never leaving their children's sides until they died or reached adulthood.
Except today's stay-at-home motherhood isn't anything like traditional motherhood, and most cave moms did work outside their caves.
It's true that when our hunter-gatherer foremothers gave birth, they usually did so in the comfort of their own caves, surrounded by women of their extended family or small community, and in their recovery period, they would stay in to breastfeed non-stop, as newborns are wont to do, and keep a close eye on their little one. Unlike today's stay-at-home mothers, though, cave moms would have a network of male and female relatives around to help with day-to-day tasks like making sure there were clothes to wear and food on the table. Once the baby was big enough to strap on and leave the house, though, she'd have to get back to one of the most important jobs anyone in this era had to do in order to survive: find food.
Once a child enough was old enough to walk and be generally self-sufficient, chances are it was usually left in the care of older children or other relatives who were too old or sick to go out on their own while cave mom went out looking for food, or the child would also have to go out and help find food. Cave mom couldn't stay home and spend all day drawing on the walls to teach her kids the names of objects and tools or singing songs about body parts. She had to work to keep her family alive. She may not have been running mammoths off cliffs, but she didn't have the luxury of staying home all the time either.
Even after humans moved out of caves and figured out farming, women would still have to go out and work the fields and do all the tasks required to keep her family alive, alongside her husband. Not only did these moms have to work, but their children would be put out to working the fields or making clothing and meals, too, at an age most of today think of being as too young and tender for much of anything but play. And farming moms often still had a network of extended family they could rely on for help raising their children and making it through the first year or two of a baby's life when their activities would be restricted by breastfeeding.
Since industrialization, there have always been women who worked outside of their homes, who would have to wake up early and leave their homes and their children, often even their babies, to go to work. It led to some pretty abysmal circumstances. A lot of mothers to little babies would be unable to breastfeed due to their work schedule, and if they couldn't afford a wet nurse (and most couldn't), would have to rely on unpasteurized cow's milk for nourishment, which often made babies very sick and killed them. (Formula doesn't sound so bad after hearing that.) And women's options for care for their children were often less than appealing, leaving many women to put their little ones in baby farms, daycare's ugly, abusive forebearer.
Stay-at-home motherhood as we think of it today is a fairly modern invention, the result of the explosion of the American middle class at the end of WWII and the sudden accessibility of most of life's necessities without both parents needing to work themselves to the bone to procure them. This came alongside the rise of the nuclear family, when moms no longer lived with their own parents and extended families, where everyone helped to raise everyone else's children. Instead of child-rearing being a community effort, it became the sole province of one person: mom.