Without reading into the claim I’m pretty sure it’s driven by the growth of the white collar middle class. whatever growth there was in women working in factories, it was surely less than the fall in women working on farms.
Yup. And work on even a small one-family farm (which all small farmers of all genders would be doing) counts as real work, because the products of that work are sold on the market.
But fast forward on some decades, and housewives working strictly in the home doing domestic labor of rearing and feeding the family and managing the household doesn't count as economic labor because none of the results of that labor are actually being sold on the market. Yes, it's enabling the husband to be more economically productive by not having to worry about that stuff, but that's a second-order effect.
I also recall reading that, in the agrarian Middle Ages, women in farming communities (though also men and children to a lesser degree) did things like spin cloth to sell during the winter when there wasn’t much work to do on the farm to bolster family income during the slow season.
As those “side gigs” moved to factory production (for cloth production that happened very early), I wouldn’t be surprised if families stopped participating due to it not being economically feasible.
But fast forward on some decades, and housewives working strictly in the home doing domestic labor of rearing and feeding the family and managing the household doesn't count as economic labor because none of the results of that labor are actually being sold on the market. Yes, it's enabling the husband to be more economically productive by not having to worry about that stuff, but that's a second-order effect.