>>213703597 (OP)
Third world birth rate is already below replacement except African and Muslim countries.
Latin America has roughly the same birth rate as the USA. Thailand has worse birth rate than Japan. In the USA, African American birth rate is also low.
Chuds will hate the answer but the only way for less civilized people to breed less is to raise their standard of living, bring them into Judeo capitalism: depression, putting economic and personal pursuits before marriage, gender war, incelism, women's right, urbanization, less religiosity