There's a new baby blog at Slate.com called "How Babies Work". The first post is about the science of breastmilk and it's really interesting:

http://www.slate.com/blogs/how_babies_work/2013/03/20/the_science_of_breast_milk_latest_research_on_nursing_and_milk_vs_formula.html

I love reading about the science of babies and pregnancy so this should be good!