In societies where families may have to see their children die due to poverty and the accompanying ill health, where education has not yet brought contraception, it's not a matter of health, but of survival and day-to-day life. She may have given birth 20 or 30 times, to have 15 living children.With rising income and education, family sizes tend to fall. Loans that help them have confidence in the future, a society that doesn't rely just on surviving children to look after the old, and better health through better nutrition can all help people have confidence in the need to have fewer children. Go back 300 years i the history of the Western Nations, and 15 children wasn't that uncommon! Not healthy maybe, but what is, and that that many have survived should be a matter for celebration.