If men strive, and hurt a woman. 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 fœtus, 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.
John Calvin in Commentary on the Four Last Books of Moses, on Exodus 21:22