There was a science fiction story I read about that once, an alien species that would die if they didn't give birth every year. I think they tried everything from hormone modification to mass baby dump pits but they couldn't maintain a stable society for longer than about fifty years when overpopulation killed everyone, so thrt just gave up.

Actually more than one, because I also read one about scientists deciphering messages from aliens who used the word for "baby eater" to mean "good"