Or people could just start having less kids?
"The number of children desired or considered ideal remains highest in western and middle Africa
with an average of 6 children desired. About 70 percent of women who have 4 children still want more
children in this region. In southern and eastern Africa, the picture is significantly different with an
average of 4.5 children desired and an average of 42 percent of women with 4 children who want more.
The desired number of children is much lower in countries in North Africa, Asia, Latin America and the
Caribbean, ranging from 2 to 4."
http://www.populationmedia.org/2010/...r-of-children/