You have to be careful to not stimulate child birth that way. In South Africa there is a stipend paid for each child (called social grants). It's debatable but many claim it does encourage poor mothers to have even more children (the stipend isn't enough to support each child fully [3]- it's about $20 per month), and is sometimes used for other purposes.[1][2]

[1] http://www.sowetanlive.co.za/news/2012/05/25/misuse-of-socia...

[2] http://www.iol.co.za/news/south-africa/grants-used-to-suppor...

[3] http://www.parent24.com/Baby/Toddler_1-2/care_nutrition/The-...