Fertility Rates by Education Level

I just read that women in Ethiopia who haven't gone to school have an average of six children, while the women who have a secondary education have two children. This made me wonder what the stats are for women in the US. I'd definitely think that women with less education probably tend to have more kids, but how many more? I asked Jake what he thought the difference was, and his initial response was that he thought that women with a high school diploma probably have, on average, 1 more kid than women with a bachelor's. I wonder if it is even that high...That difference of four kids in Ethiopia is incredibly high. I suppose that was surprising.

I'm not sure where to look up number of kids by education level in the United States. Does anyone have suggestions about places to look? I sort of doubt that it's within Census information at all. It'd be a bit tricky to get accurate information on this. The numbers might change generationally, and a final number of children couldn't be calculated until a woman has finished her reproductive years.