When Spain increased parental leave for men, desired fertility dropped. Some men want to do childcare, but a substantial cohort want to chase comp and status while someone else stays home to raise their kids.
The phrase I’ve heard more than once about this is “Men want kids like kids want pets.” Easy to want something, but work is hard.
https://www.theguardian.com/world/2019/may/20/paid-paternity...
https://www.sciencedirect.com/science/article/abs/pii/S00472...