The Australian philosopher Peter Singer is a preference utilitarian, and has argued that infanticide should be legal, on preference utilitarian grounds. He argu

The Australian philosopher Peter Singer is a preference utilitarian, and has argued that infanticide should be legal, on preference utilitarian grounds. He argues we have to treat the preferences of all beings equally, but newborns have no concept of what it means to continue to live, so can’t possibly have a preference/wish/desire to go on living. Hence, the only moral obstacle to killing them is the wishes of their parents, therefore (painless) infanticide should be legal with parental consent. Personally I find his view to be utterly morally abhorrent, but I have to credit him with the courage and consistency of taking utilitarianism to its logical conclusion.