" To argue against abortion on the grounds that it prevents beings of high intrinsic value coming into the world is implicitly to condemn practices that reduce the future human population: contraception, whether by ‘artificial’ means or by ‘natural’ means such as abstinence on days when the woman is likely to be fertile, and also celibacy. This argument does not provide any reason for thinking abortion worse than any other means of population control. If the world is already overpopulated, the argument provides no reason at all against abortion. "

― Peter Singer , Practical Ethics