Hunter-Gatherer Parents: Better Than Today's Moms and Dads? - The Daily Beast
It's funny that you don't think the two go together, because the majority of hunter gatherers mostly ate food that was gathered, which was primarily gotten by women. So as far as feeding people, women were doing a lot more "bread winning" than men.
Furthermore, women didn't have very many children. Usually just 2 or 3, spread between 4 and 10 years apart. They spent the majority of their lives not beholden to very dependent young children (and like I said, even if they did have young children, they didn't always mind them themselves).
This idea that sitting at home with a litter is "feminine" is new to isolated patriarchal models.
As far as hormones, we do know the body converts them to estrogen and uses them as such. As far as birth control, the hormones are expelled in urine and very hard to eliminate from water, so it's entirely possible that's part of the impacts.