Also, I am sure you are aware that Indians (from India) have historically limited the number of girl babies for this reason. I suppose the Chinese preference for boys also acts to keep population down one generation later.A problem though is all the very angry and aggressive leftover young poor men without women.
Peter Turchin of “Secular Cycles” observes that allowing rich men to have four wives increases population growth. If a one man/one woman system is followed, then many women are left without husbands because many poor men cannot afford to have wives and families. If rich men can have four wives, this practice absorbs the would-be excess women, and lets them have children. - Gail Tverberg