Well you have to take birth control constantly and a lot of very young women end up having it. You could easily wipe out a generation of fertile women if you didn’t do it correctly. On the flip side, old men (usually) that sometimes need to use a pill doesn’t seem all that dangerous.
It’s crazy to think about but we may soon be in the dystopian future where everyone has a rebreather system while they walk around in grungy neon lit cities. It’s preparing us for what colonizing other planets might look like I guess.