If we were to think of it in terms of a scale, with one end of the scale being no education, and the other end being the most well educated in the world, the closer a population as a whole was to the "no education" end of the scale, the higher the birth rate would be, and the closer to the "most well educated in the world" end of the scale, the lower the birth rate would be.

Studies show that the single greatest influence in bringing down the birth rate of any given population, is educating the women of that population.