Working gives more security for a woman and her DCs, e.g. to avoid a massive drop in their standard of living, if her OH buggers off with a younger model and cba to support his kids.
Or he may die suddenly, or become unemployed.
Also, if the relationship becomes abusive, the woman has more options to take the kids out of that situation if she has a job and her own money.
These factors could affect educational outcomes and life chances.