Hi, congrats on your preg!! I'm like you, I have had 2 previous pregnancies (5 and 2 1/2 years olds) and now I'm 18 weeks pregnant with number 3! I too had treatment to my cervix (LETZ procedure a year ago for CIN 3.)
I was really stressed about the pregnancy and had so many questions and got myself even more stressed after I googled it!! The words miccarrage, incompetent cervix kept coming up. So at my appointment with my OBGYN last week I went with my list of questions!!
He was very reassuring, he said that the risks of the above meantioned were very, very small and that I needed to stop worrying. He did however meantion that sometimes in labour the first stage can take a little longer as the procedure can cause the cervical tissue to toughen (as in scar tissue) but he said as long as those looking after me in delivery were aware of this they can allow the extra time and monitor my progress closely.
The OBGYN was very understanding and said that no question is ever a silly one and always to ask, and I trust him as I had both my other children under his care. If I were you I would discuss your concerns with whoever is looking after you. It will also depend what treatment you had to remove the cells.
Hope this helps! Regards mum of 2 and 18 week blue bump!!