Incompetent cervix refers to the physical structure where the uterus opens up so the baby can be delivered. In the case of an incompetent cervix this muscle is not able to hold back the baby in the uterus.
If someone has been diagnosed with an incompetent cervix, doctors are able to put a small stitch in the cervix itself which will prevent the cervix from opening prematurely. If someone has been diagnosed with an incompetent cervix it is important that in later pregnancies the doctor is aware of this fact so that he can place a cerclage, (the stitch holding the cervix closed). When someone with a cerclage approaches full term, the stitch must be removed so that the baby can be delivered.