Check out the ethics of people-hating.
In its white paper on “The Ethical Implications of Population Growth“, Population Matters states,
3. Reproductive ethics: It is also a fact that if two people with two living children have a third child, they will ratchet up the population of the planet, and thus: ratchet up damage to the environment; bring nearer the day of serious ecological failure; and ratchet down everyone else’s share of dwindling natural resources to cope with this. So individual decisions to create a whole extra lifetime of impacts affect everyone else (including their own children) – far more than any other environmentally damaging decision they make. We need to be aware of the ethical implications of having large families; and sex education in schools should include it.