23 weeks 23mm cervix length

[Patel333]

Hello, my last pregnancy was misscarried At 18th week due to seviour abdominal pain and heavy bleeding. Now in my second pregnancy at 20th week I was undergone a cerclage, becoz of my cervix length is 24mm and Doctor suggest me to take bed rest. After 3 weeks @23, I have scanned and my cervix is 23mm, it became 1mm shorter. I am very much worried about my cervix length, so please tell me why my cervix decreased even after cerclage,and will it continue decreases the length?. If it continue decreasing what I need to do? Help me please...