In his recent letter Bill Gates has this graph that shows the correlatin between better health and less children for a family. http://www.gatesfoundation.org/an

In his recent letter Bill Gates has this graph that shows the correlatin between better health and less children for a family. http://www.gatesfoundation.org/annual-letter/Pages/2009-preventing-childhood-deaths.aspx http://www.gatesfoundation.org/annual-letter/Pages/2009-prev... (chart 3) Bill G. explained that in the begining his foundation was focused on population control. But when they discovered that the single most important factor in population was health is when they started to focus in the most crucial sickness. His explanation is that parents simply try to optimize to have two children that can take care of them when they are old.