I think it probable that the Hebrew women were distinguished with peculiar marks of divine favor in those seasons of child-bearing. Perhaps as a token to them and their husbands, that the hand of the Lord was with them. 1 Timothy 2:15.
Related Commentaries of Exodus 1:18
Exodus 1:18-19
18 And the king of Egypt called for the midwives, and said unto them, Why have ye done this thing, and have saved the men children alive?
19 And the midwives said unto Pharaoh, Because the Hebrew women are not as the Egyptian women; for they are lively, and are delivered ere the midwives come in unto them.