Lynn is right.During pregnancy,the follicule actually holds onto hair it would normally shed,which is why it seems thicker and more lusterous.
After pregnancy,the hair simply sheds these extra hairs which seems like alot sometimes.It is completely normal.I was like you and noticed more hairs coming out,but nothing major.My sister called me crying after her baby and said she lost like 500 hairs at one time. Of course,she never had a bald spot or anything,it just seemed like alot all at once.
You should look into THE GIRLFRIEND'S GUIDE TO PREGNANCY by Vicki Iovine.She explains all the things that pregnancy can cause to happen to your body and it's very helpful.