It does require more argumentation than just that though because it's also the only case where you have used your own body to create somebody else's life. Some argument for why this is not relevant would be in order.

One way to proceed is to reject the premise that there is meaningfully "somebody else" yet. This works up until about the third trimester, at which point it starts becoming questionable whether it counts as "somebody else". However, as a consequence, one could not punish violence leading to miscarriage(in the first two trimesters) as a "murder" because it's not "somebody"; one would have to justify any punishment beyond that deemed proportionate from the harm to the woman using some other scheme.

(This is not the only way to proceed. My point is only that one can't make such an observation and hang up one's hat and call it a day. It's a very powerful observation but because the situation is unique in multiple ways it needs additional support to make a complete argument.)