Teisou Gyakuten Sekai de Nariagari o Mezashite Otoko Kishi ni Natta Boku wa, Yarimoku Onna-tachi ni Karada o Neraware Makuru - Ch. 1

[JethroBodine]

Don't try to think about how any of these reverse Chastity worlds where there's a very small amount of men have been able to maintain a stable population because it doesn't make any sense and logically they should have all died out years ago due to lack of newborns.

Elves make sense because they have long lifespans so a lack of newborns isn't crippling. The other races, I don't know.