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The Cervix During Pregnancy

Updated on October 31, 2012

The Cervix and Pregnancy

The cervix is the organ that provides the entrance to the womb. It undergoes several changes during the course of pregnancy and childbirth. As the cervix plays an important role in facilitating the smooth delivery of the baby, expectant mothers will find it useful to understand how the organ works.

Stages of Pregnancy

Cervical Opening

During pregnancy, the cervix is closed, with a mucous plug blocking its opening. The mucus plug helps to keep out infection from external sources. How big is the cervical opening? For women who have never had babies, it is very small indeed. But for women who have had children before, the external opening of the cervix is the size of a small slit. The internal opening, though, remains closed. In doing so, it counteracts the pressure from the fetus and uterus lying above it. This provides some form of support and protection for the fetus.

Changes to Cervix During Pregnancy

During the course of pregnancy, the cervix undergoes several changes. It will stretch and widen. The external opening (leading to the vagina) will shorten and open slightly while the internal opening (leading to the uterus) begins to thin out. Towards the end of pregnancy, the cervix starts to “ripen”. The organ becomes softer and changes color to dark blue. As the woman starts to go into labor, the cervix undergoes the greatest changes. Formerly closed, its opening now widens to 10 centimeters to allow the baby’s head to pass through to the vagina. The cervix also effaces significantly, as it thins out and softens in order to dilate fully. At this point, some of the mucous that has been plugging the opening of the cervix may come out. That is an early sign of childbirth. As labor progresses, the cervix also begins to shift towards the center or front of the vagina.


Problems may arise with the cervix during pregnancy and affect smooth labour. However, such incidents are rather rare. A woman’s cervix may have difficulty keeping closed during pregnancy, which may result in infection or even miscarriage. This is what is known as an incompetent cervix. In this case, the doctor may perform a cervical cerclage. This procedure involves stitching the cervix to hold it closed. However, the condition is very rare and only affects about 1% of pregnant women. Another possible problem lies in the length of the cervix. The cervix of a pregnant women is usually 3 centimeters long or more. However, if the cervical length is found to be less than that, it may be the case of an incompetent cervix and premature delivery is likely. Close medical attention is necessary in the case of a short cervix.In other complications, a pregnant woman’s cervix may remain shut and not dilate. This is known as a stenotic cervix. Again, such an incidence is rare.


After childbirth, the cervix will gradually return to its previous form. However, it will not be closed as tightly as before.


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    • profile image

      Lmyaa 4 years ago

      I am 37 weeks pregnant and I ttaolly understand why you are crabby! I am so crabby and irritable. I cannot wait until this is over!! I was over due with my first child, by two weeks. I am assuming that I will not go into labor anytime within the next three weeks but I am certainly hoping so. I got my cervix checked at 36 weeks and 5 days and I was only one centimeter dilated so you are lucky you are already at two! Anyway, good luck with everything!

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      clare 7 years ago

      great article :)

    • H P Roychoudhury profile image

      H P Roychoudhury 7 years ago from Guwahati, India

      It would be very helpful to all pregnant women. Thanks.