Seforno: When he issued the command to kill the babies, they accepted it, with the result that he expected them to carry out his orders, and now that they did not, they had let him down.

Oznayim la'Torah: Pharaoh did not expect them to kill the babies once they were born - or even to withhold from them food. ¹ What he wanted to know as why they were confining their activities to helping the babies after they were born and not to carrying out the actual birth - where they would be able to carry out his instructions.