The extreme cruelty of the measure does not involve improbability. Hatred of strangers was always a characteristic of the Egyptians (see Genesis 43:32), and was likely to be stronger than ever after the expulsion of an alien race.
Related Commentaries of Exodus 1:22
Exodus 1:22
22 And Pharaoh charged all his people, saying, Every son that is born ye shall cast into the river, and every daughter ye shall save alive.