According to The Economist (hard copy), in 1960, the average Brazilian woman has 6.3 children in a lifetime, while this number dropped to 2.3 children per lifetime by 2000. This happened despite (of because of) military rule for much of that time period.
There are lots of lessons that could be learned from this dramatic change in a basic element of family life and culture in Brazil, that has parallels in countries all across the world as they experience economic development in similarly short spans of time (including Mexico amd China). While China poses an example where this change was imposed forcefully, in Brazil contraception was gently discouraged for part of the 40 year period in question, and Mexico has, at the very least, imposed strict legal prohibitions on abortion.
The big picture lesson I choose to draw is that dramatic social change can be secured in a generation or two. The dramatic increase in the number of women in the professions in the 1970s and 1980s, and the demise of the legitimacy of de jure segregation or open racial discrimination per se, even among far right conservatives (including many prominent segregationist politicians) repeat this point. The present is not destiny, and dramatic social change is possible in considerably less than a single lifetime.