I had an abnormal smear this year (severe dyskaryosis/CIN3) and had to have a colposcopy to examine them, and then treatment to remove them.
I had to still attend a check up this week and found that they hadn't removed all of the cells. They still performed the colposcopy (legs up, look up you with binoculars on sticks and paint cervix with a solution to look for abnormal cells). I was informed that if there were a lot of abnormal cells they may treat me in my final trimester. Luckily she decided to wait until after the birth (3 months) till I have further treatment. She did offer to do a smear to get a further idea of what was there (she was sure there was no risk with me being pg), but as I wasn't going to have treatment until after the birth I decided it was something extra for me to worry about. You have to decide for yourself what you are comfortable with.
I saw my cervix on camera each time - in April there were bright white patches all over my cervix and now there is a faint white bit just around the whole.
It all depends on the severity of the abnormal cells. Mine were the most severe but if you have CIN1 they would probably just leave it and keep an eye on it. I think they only tend to treat when it is CIN2 and 3.
I am glad i'm pregnant now and although I am a bit concerned about waiting, I would have to be extremely unlucky for it to turn into cancer (takes years apparently). I know someone at work who had CIN3 picked up at smear but fell pregnant straight after. They didn't treat her till 4 months after the birth and she was and is fine.
You can still have a colposcopy when pregnant which would give you a better idea of how severe it is ( but without scraping your cervix!), or just make sure you get it looked at before gettign pregnant again.