Of course it was devasting for some families. That is never the same thing as saying that it affected China's birth rate much (which it didn't).

There were forced abortions (sometimes very late), there was forced contraception, forced sterilization (I think), and lots of punishments for people who broke the policy.

There were also others who got around it fairly easily by paying a bribe and by not registering their "surplus" child/children (especially if they were girls). That of course caused some problems down the road.

That still doesn't mean that it affected China's birth rate much. It was already low (and had fallen steadily) when the policy was instituted. It also had plenty of exceptions for rural China and ethnic minorities.