'"If some men are fighting and hurt a pregnant woman so that she loses her child, but she is not injured in any other way, the one who hurt her is to be fined whatever amount the woman's husband demands, subject to the approval of the judges. But if the woman herself is injured, the punishment shall be life for life, eye for eye, tooth for tooth, hand for hand, foot for foot, burn for burn, wound for wound, bruise for bruise."' Ex 21:22-25 GNB
The concern here is not with murder, but with manslaughter, accidental death. A man who is fighting another, whose wife intervenes and receives a blow from him that kills a foetus, does not intend for the harmless foetus to die. There was economic loss in such cases (potentially, anyway- childbirth was hazardous before modern times), so reparation was necessary. However, if the man used sufficient force to kill the wife, the standard law of
lex talionis applied, because it was reckonable as murder.