My hair shed pretty bad during the first half of the pregnancy. It was a mess! I found out that I was anemic, and the Dr prescribed iron supplements. After that, my hair stopped shedding and it was much better to deal with. It grew while I was pregnant, but I don't think it was the pregnancy. I think I just had great retention because my hair was in a ponytail or bun for most of the pregnancy.
DD is almost 8 months, and I haven't had any PP shedding. (THANK GOD!!!) I kept taking the prenatals and iron consistently through the first 4 months, and now I take them when I think about it, but not every day. I also keep my hair pulled back most of the time because DD pulls it and it gets in the way.