I sure you guys can list others but here is a thought about the exodus story. In chapter 1 the Pharoah is concerned that the israelites are becoming to numerous. And just as a side point we can assume Pharaohs were not to dumb and even if they were the smart people of Egypt studied in the temple 40 years and they studied all things not just religion. I'm sure the Pharoahs had advisers.
Ok with that said would it not be way more effective to kill the girl babies of Israel not the boys? If you don't get my point a rancher if wanting to grow his herd he will have many females, yet only needs a couple of males.