The goal of a cerclage is to hold the cervix closed. This lets the baby fully develop before birth. Cerclage is done at about week 12 of pregnancy. The doctor gets to the cervix through your vagina. They put a stitch in the cervix. At week 37, the baby should be ready for life outside the womb. At this time, the doctor removes the stitch. This lets the cervix open when labor starts. Once you have a cerclage, you will likely need this for each future pregnancy.