You're assuming an unwanted, unborn baby has value. Not only does it not have value, but it's actually a burden to society. Utilitarianism would consider the damage that unwanted, unborn baby will inflict on society and decide to abort it every single time. Social welfare, orphanage, and especially criminal costs are incredibly likely and incredibly high. The chance that the baby will amount to anything worthwhile enough to offset those costs is incredibly low for an unwanted baby and thus not worth the risk to society. Here in the US we have seen the criminal costs of outlawing abortion with the high crime rates of the 70's, 80's, and early 90's finally coming down in the last two decades due to legal abortion. Other countries like Romania know this equally well. That doesn't even begin to take into account the rest of the social costs of forcing unwanted babies to be born.