Most of the rise seems to be linked to demographic, economic and societal factors, which have been largely tied to the rise in immigration. And while the lion's share of SAHMs do seem to come from "traditional" married households, there are still significant numbers who are single, living with out-of-work husbands or just plain unable to find work. Others are in this club due to a disability, or because they're working toward a degree and can't juggle the kids, balance classwork and work a full-time time simultaneously. (Which sounds exhausting just to think about.)
For this other group of SAHMs—the ones who don't hail from "traditional" married households, with a husband's income to at least somewhat cushion them—their reasons for staying home are not by their own design. While 85 percent of married SAHMs reported that they stay home primarily to be caretakers for their kids, only 41 percent of single moms and 64 percent of "cohabitating" moms claim that to be the case for them. For those moms, other more trying factors are at play.
And now for the most upsetting stat to be revealed by the study: 34 percent of SAHMs live in poverty. As for working moms living in poverty? They account for a much smaller (though still disturbing) 12 percent of the female workforce.
As the study notes, a lot of this has to do with demographics:
"Stay-at-home mothers are less likely than working mothers to be white (51% are white, compared with 60% of working mothers) and more likely to be immigrants (33% vs. 20%). The overall rise in the share of U.S. mothers who are foreign born, and rapid growth of the nation's Asian and Latino populations, may account for some of the recent increase in the share of stay-at-home mothers."
And as for those so-called "opt-out" moms? The Pew report cites that they are few and far between—only 5 percent of SAHMs actually fall into this category. They also tend to be older (half are between the ages of 35 and 44), and "disproportionately" white or Asian.
You can read the rest of the study's findings here.