I came across Exodus 21:22-25 while performing research for my rebuttal to a reply by C_Andy_3. I would like to thank C_Andy_3 for the discussion that led to my discovery of this passage.
Old Testament quote, emphasis mine (thanks to Mechon Mamre for the RaMBaM translation):
22 And if men strive together, and hurt a woman with child, so that her fruit depart, and yet no harm follow, he shall be surely fined, according as the woman’s husband shall lay upon him; and he shall pay as the judges determine.
23 But if any harm follow, then thou shalt give life for life,
24 eye for eye, tooth for tooth, hand for hand, foot for foot,
25 burning for burning, wound for wound, stripe for stripe.
This clearly states that the fetus was not a life. In fact, it indicates that a miscarriage could be caused without causing harm. The loss of the fetus can be compensated by mere money. After that, if there is harm, it is life for life, eye for eye, tooth for tooth, ….