Population ethics is the branch of normative ethics that attempts to justify and articulate principles for making choices between alternatives involving different people. These differences can consist in changes either in the number of people affected or only in the identities of these people.
Aird, Michael (2020) Collection of evidence about views on longtermism, time discounting, population ethics, significance of suffering vs happiness, etc. among non-EAs, Effective Altruism Forum, May 10.
Many additional resources with some relevance to this topic.
Arrhenius, Gustaf, Jesper Ryberg & Torbjörn Tännsjö (2006) The repugnant conclusion, Stanford Encyclopedia of Philosophy, February 16 (updated 16 January 2017).
Greaves, Hilary (2017) Population axiology, Philosophy Compass, vol. 12, pp. 1–15.
MacAskill, William & Darius Meissner (2020) Population ethics: The total view, in ‘Elements and types of utilitarianism’, Utilitarianism.