With my first pregnancy, my doctor told me he would rather wait to do any biopsy's till after the baby was born because it can put you at risk for pre-term labor. He said a lot of times the uterus is going through so much healing after the baby is born that the bad cells usually go away on their own. As long as you're not getting any biopsy's then you should be ok. The colposcopy is just to look at your cervix to see how bad the cells actually are.
I just now noticed that alaysha answered this question pretty much perfectly!! :-P
Not going to hurt you at all. They will only do a colposcopy while pregnant but they will not do the biopsy part (actually taking cells). What happens is like with a pap they look into your whoo ha and a doctor will swab it with vinegar. It kinda tingles but all they are looking for is white spots to see how bad the infection has spread. They can't really do anything about it during pregnancy and a lot of time because of natural changes to the cervix during pregnancy it will go away on its own after you give birth. They will do another colposcopy after you give birth to check to see if things have improved and if not then they will do the actual biopsy part. I got it done a little earlier on in my pregnancy and even though I'm high risk it caused 0 side effects.