I remember watching a documentary a few years back about a program that was trialed in...in...I want to say India but I don't think it was. Anyway some country where people (especially rural) married young and just kept producing children until they couldn't anymore. They did so traditionally, their parents and grandparents would have lots of kids because infant mortality was so high.
Now, most children born there survived past five yrs and the couples ended up with too many kids to care for. So they trialed sending family education social type workers into the field to visit all the families and explain how if they had too many kids the quality of care and amount of resources for each child would drop as each child was born putting a lot of stress on the family as a whole. They provided free birth control and did follow up visits they were amazed at how the couples took the advice on board and the birthrate/average number of children dropped for that area in a couple of years.
It was very interesting to see what can be done with minimum effort and outlay for a simple amd effective education program.