Calvin comments on Exodus 21:22-25:

“The fetus, 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 life which it has not yet begun to enjoy. If it seems 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 fetus in the womb before it has come to light.”

“If men struggle with each other and strike a woman with child so that she gives birth prematurely, yet there is no injury, he shall surely be fined as the woman’s husband may demand of him, and he shall pay as the judges decide.  But if there is any further injury, then you shall appoint as a penalty life for life, eye for eye, tooth for tooth, hand for hand, foot for foot, burn for burn, wound for wound, bruise for bruise” (Exodus 21:22-25).