A sociologist suggests mothering is done very differently in America:

“American parenting is child-centered, expert-guided, emotionally absorbing, labor-intensive, financially expensive and is expected to be done by mothers alone. And it is impossible to do alone,” said Sharon Hays, a sociologist at the University of Southern California. “The mothering you see today in America is culturally and historically unprecedented. We expect selfless devotion to what we interpret as the child’s needs, wants and interests at every moment of the day. And with the vast majority of mothers working, that puts them in an impossible paradox.”

While the intensity is at its most acute in the middle and upper-middle class, she said, her studies have found that low-income parents feel the same parenting pressures, compounded by the guilt of having neither the resources nor the time to meet them.

The rest of the article talks about why this is: we have structured society in such a way so that the brunt of child care is borne by individuals, not society, and with our cultural gender norms, women are left with much of the burden.