For 9 months, the cervix stays tightly closed to protect baby growing in your womb. As D-Day approaches, the pass begins to transform.
What is the cervix?
The uterus is pear-shaped, and for nine months the baby grows in the upper part, which is rounded. The elongated and narrowed part is called the “neck”. This is about 3 to 4 centimeters long, has a diameter and a small opening: it is through this that the menstrual blood flows and that the sperm are introduced. At the start of pregnancy, this opening closes, creating a protective barrier for your baby, which is sealed by the mucous plug.
As D-Day approaches, the pass begins to transform. In fact, in order for you to give birth, the cervix will have to open to let your baby pass through, and in the days preceding the birth, the cervix undergoes essential changes before going into labor: c This is called cervical ripening. First, it softens and shortens: we then say that it fades. You may also have heard the terms col effaced or cervix effacement. Then, under the effect ofcontractions, it opens on an increasingly larger diameter: it expands.
Cervix dilation during pregnancy
However, it happens that the cervix begins to change, even to dilate more too much in pregnancy (before the 9e month). Several factors can explain this undesirable phenomenon, such as a weakness of the cervix, a too small or badly formed uterine cavity, a premature rupture of the bag of waters, an infection (such as a urinary tract infection), an infection of the cervix… These disorders can indeed be the cause of contractions of the uterus which, in turn, lead to changes in the cervix. Without medical intervention, this can result in premature labor.
This is why the cervix is closely monitored throughout pregnancy, especially if you have frequent uterine contractions. A doctor or midwife can then check the length of your cervix by performing a vaginal examination.
If the cervix changes a little, you may be prescribed rest or sick leave. You may also be forced to stay in bed. If your cervix shortens or opens significantly, hospitalization may be necessary to ensure your well-being and that of your baby. There, the necessary treatments will be administered to you.
The gaping cervix
We speak of openness of the cervix when the orifice does notdoes not play its role of lock and relaxes, even if there are no contractions. This may be due to a malformation of the cervix, or even a loss of muscle tone. The open cervix can lead to miscarriage in early pregnancy or premature delivery. Fortunately, this serious condition is rare, but if you suffer from this uterine weakness, cervical cerclage may be performed. This surgical technique consists of keeping the cervix closed with a strong thread and aims to prolong the pregnancy until the baby reaches term.
Get to work
When baby is ready to be born, the cervix can (and should) open. This is only possible with effective contractions. It is the alternation between the contractions and the phases of relaxation of the uterus which is the very engine of childbirth. Combined with pressure from the water bag and baby's head (or buttocks, in case of a breech), the contractions allow the cervix to dilate.
During labour, the cervix therefore changes in texture, position and stage.
- Modified: These changes can occur a few days or even a few weeks before D-Day. Gradually, the cervix which, during pregnancy, is oriented towards the back, will center with the vagina. It softens and may even open an inch or two.
- Shortcut: The cervix is shortened, under the effect of contractions which pull the cervix upwards. It thus goes from mid-length toshort, to thick, to erased. All women are different and this step can take several days, or just a few hours.
- Dilated: Still under the effect of contractions, the cervix will open little by little. Full dilation corresponds to an opening of 10 centimeters. As soon as you arrive at the maternity ward, the nurse or midwife performs a vaginal examination and measures the size of the opening with her fingers.
The expansion phases
- Latency phase: During this phase, dilation can advance up to 3 centimeters. Your contractions, of low intensity, return approximately every 5 to 30 minutes and last 30 to 45 seconds. During a first delivery, this phase can last from 7 to 10 hours. It is shorter during subsequent deliveries.
- The active phase: The contractions have intensified. Every 3 to 5 minutes, they are also longer (40 to 70 seconds). The cervix opens up to 7 centimeters.
- The transition phase: During this last stage, the cervix reaches an opening of 10 centimeters. Everything intensifies and the contractions, even closer together, are at their strongest.
It is estimated that the cervix should dilate one centimeter per hour, but this rate is not regular and varies between women. Moreover, the first centimeters are often the longest (latency phase). On average, cervical dilation can take up to 13 hours for primiparous and 7 hours formultiparous. This is an average: for some women it all happens very quickly, for others it takes much, much longer.
Sometimes the dilation of the cervix does not progress fast enough or stagnates, often because the contractions are not intense or frequent enough. The mother is then encouraged to move, to change position, to walk. If this is not enough, we can also pierce the pocket of waters. This usually results in stronger contractions and more pressing of the baby's head on the cervix. The woman may also be given an injection of oxytocin, which will increase the duration, intensity and frequency of the contractions.
If, despite everything, the dilation stagnates, we may proceed to a caesarean section. When a induction of labour is necessary (passage of the term, rupture of the bag of waters before the onset of labor or other complications) and the cervix is not favourable, we apply a tampon containing prostaglandins in the vagina to make it mature.