You're unnecessarily turning this into sexism issue, ironically ignoring how men also have a part in birth rate. All humans, men or women, have agency, but they

You're unnecessarily turning this into sexism issue, ironically ignoring how men also have a part in birth rate. All humans, men or women, have agency, but they're most likely going to act in their best interests. That's why we can generalize large scale behavior with some degree of accuracy. Obviously that's the not going to capture the nuances of every individual decision, but that's the best that we can do when discussing the effects of policy.