How Dilation Is Measured In Labor

Dilation is the expansion that occurs in the uterus to allow delivery. This progresses gradually, in a process that lasts several hours and even several days in some cases.

The process of dilation is accompanied by contractions. It constitutes the first stage in labor. During it, a series of modifications takes place that will allow the passage of the fetal head through the birth canal.

Dilation needs to be measured to know how far labor has progressed. This is determined by the degree of opening of the cervical os. This reaches 10 centimeters at the time of giving birth.

What is the proper dilation for childbirth?

The uterine dilation process begins when the cervix begins to expand and ends shortly before giving birth. Different phases take place between these two points that provide information about the evolution of labor.

Dilation is measured to know if the delivery progresses normally. It should be remembered that during pregnancy the cervix must remain closed. When labor approaches, it begins to open up.

The process is preceded or occurs simultaneously with the expulsion of the mucous plug and the rupture of the source. In a moment we will talk about how this process progresses; that is to say, on the phases involved in the dilation.

Phase 1

Phase 1 of labor has a variable duration. Typically, it takes longer for new mothers than for those who have already had children. Nevertheless. this is not a fixed rule. This phase is also known as "latency" or "latent".

In this first phase, the cervix softens and shortens: it is a kind of initial preparation for childbirth. The main characteristic is that there are still no contractions regular nor strong: there is no pain or the pain is very mild. It concludes when the dilation of the cervix reaches 3 centimeters.

Phase 2

Phase 2 corresponds to active labor. Little by little, the contractions start to get stronger, longer and closer to each other. The cervix opens at a more regular rate and more proportionally every hour.

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The normal thing is that during this stage the dilation advances from 4 to 7 centimeters. As in the previous case, the duration is variable. At the end of this stage, which is also known as the "active phase," the mother is very close to giving birth.

Phase 3

Phase 3, or "fast acceleration," is the last stage in the dilation process.. It occurs when the fetus has descended through the maternal pelvis and the head fits into the cervix.

Under these conditions, the dilation increases in speed to allow the baby's head to pass. The cervix reaches 10 centimeters opening, with which the birth becomes possible.

How is it usually measured?

Dilation should be measured to monitor the progress of labor. Although there are devices that allow measuring the degree of opening of the cervix, the most usual is that the measurement is made by vaginal examination.

This is a procedure in which the woman must lie on her back, with her legs spread apart. The doctor or midwife inserts the index and middle fingers into the vagina until they reach the cervix.. Once there, they spread their fingers as if they were a compass to "measure" the degree of dilation.

Although the resulting measurement is not exact in numerical terms, experience allows a very approximate calculation. This procedure is not painful, but it can be uncomfortable. In all cases, it must be done with the mother's consent, who must be informed in detail.

Typically, two vaginal examinations are performed during labor. to measure the advancement of dilation. The first is done when entering the hospital and the second when it is estimated that full dilation is close.

Possible risks of vaginal examination

Vaginal examination is a risky practice when there is a placenta previa. This is a condition in which the baby's placenta partially or totally obstructs the cervix. If not reversed before delivery, she will require caesarean section.

Vaginal examination is dangerous in these cases, since you run the risk of causing a hemorrhage. If this happens, both the life of the mother and the baby are put at risk. Therefore, it is contraindicated in the case of placenta previa.

Is dilation always a sign of near labor?

If the dilation of the cervix does not occur or does not progress, in some cases additional maneuvers must be used to facilitate it. Sometimes it is only necessary to artificially rupture the fetal membranes or break the source. Other times labor must be drug-induced.

Many women are dilated towards the end of pregnancy, but this does not always mean that labor will occur soon. Sometimes that initial dilation does not progress for days or weeks even. It is advisable for the mother to speak with the doctor if she has any doubts in this regard.