You'd be surprised. Longer breastfeeding suppresses ovulation and menstruation, so fertility is relatively rare. Childbirth works better squatting. Humans evolved to be hunter gatherers, most of our history is pre-settled-agriculture, we do fit that lifestyle better.
And patriarchy was never contingent on those things anyhow. It's just a cultural choice that got stuck because it was woven into the form of citified civilization.