Falling Birth Rates as a surprise

 Birth rates in countries around the world are falling. This is the expected outcome of development and occurs as populations get richer - the idea is that as education increases, more resources are spent to educate a few children that many needed for manual labor.

But this is not proven a complete explanation. Looking at the data in the image below, all countries with large populations, advanced or not, have dropping birth rates. I think a contributing factor must also be the wide availability to birth control.