Incompetent Cervix

Sadly, miscarriages are very common during the first trimester of a pregnancy. But when a woman loses her baby during the later stages of the pregnancy, it is more likely that there is an underlying medical problem that caused the loss. One of the possible culprits is an incompetent cervix.

What is an Incompetent Cervix?
The cervix is the gateway between the uterus and the birth canal. When a pregnant woman goes into labor, her cervix begins to open up, or dilate, in order to allow the baby to pass. During pregnancy, the cervix remains shut, keeping the fetus and the amniotic sac in place.

In one out of every 100 pregnancies, the cervix will yield to the pressure of the growing fetus, and begin to open. This usually occurs at about the 13th week of the pregnancy. This phenomenon is known as incompetent or weakened cervix.

As the cervix dilates, the amniotic sac that holds the fetus will begin to stretch downwards, eventually breaking, resulting in a spontaneous loss of the baby or preterm delivery. It is estimated that 20-25% of all second trimester miscarriages are actually spontaneous losses brought on by incompetent cervix.

Miscarriages and spontaneous pregnancy losses are not the same. Miscarriages usually occur early in the pregnancy � in the first three months � and a spontaneous loss, or stillbirth occurs into the second or third trimester.

Causes of Incompetent Cervix
An incompetent cervix can be brought on by:


  • Fetal exposure of the mother to Diethylstilbestrol (DES)
  • Malformed uterus or cervix as a result of birth defect
  • Previous cervical surgeries or biopsies
  • Previous births, particularly difficult births
  • Cervical trauma from an event such as a D&C
  • Repeated late term abortions


Unless they have the risk factors listed above, most pregnant women are not checked for cervical incompetence. If, however, a woman has experienced three or more spontaneous pregnancy losses in the second trimester of their pregnancies, it is generally assumed that she has a weakened cervix. The chance of losing three consecutive pregnancies in this way and not having an incompetent cervix is less than 1%.

It is important to note that diagnosis of incompetent cervix is difficult, and in some cases where it is suspected, the problem turns out to be something else.

If cervical incompetence is caught early, it is possible to prevent the loss of the pregnancy. Using a procedure called cerclage, a doctor will place one or two stitches into the cervix, which will hold it shut while the baby develops and then be removed in the ninth month to facilitate birth. Medications may be prescribed in conjunction with cerclage in order to help prevent pregnancy loss. The success rate for this method is good, 85 to 90% of pregnancies where cerclage is employed result in a health baby.

In cases where cervical weakness occurs late in the pregnancy, bed rest and medication are usually prescribed.

Unfortunately, once a cervix has been weakened, there is nothing that can be done to strengthen it. But usually preventative measures, such as early cerclage and drug therapy, have helped many women who suffer from incompetent cervix to carry healthy babies to term.


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