Exactly the same thing happened to me. I was 20 weeks. The good news is everything went well
so try not to worry. I was so worried. I had two MRIs during pregnancy so they could check there was no growth. I refused the third as I was due to delivery yeo weeks later so I didn't see the point. After much negotiation I was allowed to go to 35 weeks. I had to have a classical c section so they avoided to cervix. My little girl was born weighing 5ib 8oz, she didn't need any extra help. Only consequence for her = weak lungs so colds etc go to her chest and she can't stand hand driers. Must have been the noise from MRIs.
As for me they left me allow for 5 weeks after the birth to give everything time to contract then straight in. Cone biopsy which found high grade pre cancerous cells, tracelectomy with node removal first then the tracelectomy. Only downside was no breast feeding after week 5 due to hospital stays. I expressed and froze the milk.
Follow ups every month, then every 6. Currently year three and checks every 9 months. I had 1b1. In the process of trying for baby number 2.
It was a hard time but my little girl was fine. I made sure I drank loads of milk. Don't know if that's why she was so strong but she came out fighting. Go with it, let the system take care of you and just be ready to go in pretty much after the birth. I reckon I was back on my feet by June. My baby was born in April.
Try not to let it overshadow your pregnancy- enjoy every second.