John Calvin [AD 1509-1564] was a french theologian who became a prominent leader during the protestant reformation of the sixteenth century.
This passage at first sight is ambiguous, for if the word death only applies to the pregnant woman, it would not have been a capital crime to put an end to the foetus, which would be a great absurdity; for the foetus, though enclosed in the womb of its mother, is already a human being, (homo,) and it is almost a monstrous crime to rob it of the life which it has not yet begun to enjoy.
If it seems more horrible to kill a man in his own house than in a field, because a man’s house is his place of most secure refuge, it ought surely to be deemed more atrocious to destroy a foetus in the womb before it has come to light.
On these grounds I am led to conclude, without hesitation, that the words, “if death should follow,” must be applied to the foetus as well as to the mother. Besides, it would be by no means reasonable that a father should sell for a set sum the life of his son or daughter.
Wherefore this, in my opinion, is the meaning of the law, that it would be a crime punishable with death, not only when the mother died from the effects of the abortion, but also if the infant should be killed; whether it should die from the wound abortively, or soon after its birth.
From Calvin’s commentary on Exodus 21:22