[Dynsei]

There's probably some estrogen during pregnancy. It's prolactin and progesterone that are way higher. I just disagree with that quote, because it conflicts with everything else.

These are the levels of progesterone and prolactin during pregnancy.
http://www.nlm.nih.gov/medlineplus/ency/article/003714.htm
http://www.nlm.nih.gov/medlineplus/ency/article/003718.htm