I had an emergency ultrasound yesterday because my uterus wasnt measuring right with the tape for…

I had an emergency ultrasound yesterday because my uterus wasnt measuring right with the tape for weeks. But hes a little chunker 4 lbs 4 oz already. They will check with ultrasound every week instead of the tape. But once your cervix has started thinning can it grow back??? I was 2.1 like 6 weeks ago the tech said it was 2.7 but she couldnt really tell because she wasnt allowed to do Transvaginal because I'm so high risk.