For a baby to be born through vaginal delivery, the woman needs to have enough space, sufficient dilation for the baby to be born. Cervical dilation for vaginal birth happens differently for each woman1. Some experience contractions accompanied by pain, while others don’t feel any pain at all, but it’s essential that complete dilation is present, that is, around 10 centimeters. But how does dilation happen? Is it possible to dilate without noticing?
Cervix
The cervix is the extension of the uterus, which should measure at least 25 mm. Anything less is considered a short cervix. It can measure from 25mm at the 20th week of pregnancy up to 32.5mm at the 34th week. We can say that the closer you get to labor, the shallower the cervix becomes. The weight of the uterus causes the cervix to get closer and closer to the vagina. It is also possible for the cervix to already be a few centimeters dilated around the 35th or 36th week, precisely because of the weight. The placenta, baby, and amniotic fluid influence this a lot. A woman may have about 1 or 2 cm of dilation without any risk of imminent labor for several weeks, sometimes until the end of the 41st week of pregnancy.
Start of dilation
Dilation really begins when certain hormones signal that it’s time for labor. Along with spaced contractions, which are not yet painful, the cervix starts to thin out (becomes softer), and the distance of 3.5 to 4 cm that exists to the vaginal opening becomes smaller and smaller to facilitate birth. For dilation to occur, it’s not necessary for the cervix to be completely thinned out. It can start to dilate even before it becomes totally thin.
The phase of cervical effacement can be quite intense and painful for some women, as some take much longer to dilate than others2. Labor can go on for several hours, just waiting for the total dilation that’s necessary. The exact time will depend on each woman and can vary, for example, if she has already had other children. The progression of dilation may be very slow, but typically during active labor, the progression is about 1 centimeter per hour.
The first 5 centimeters of dilation are usually the slowest. This is not a general rule, just an observation made by some professionals who deal with labor daily. On the other hand, there are women who dilate very quickly. In about 2 to 4 hours of latent labor, they can already have nearly complete dilation!
What makes these two types of dilation different? The body. Sometimes, the fact that the woman has had more children can also help dilation happen faster. In this case, dilation can last for less time, about 12 hours.
Most of the time, doctors choose to let dilation happen naturally. But if necessary, they may intervene with intravenous medications, such as oxytocin, break the water, advise the mother to take a hot shower, or do some exercises to stimulate induction of labor.
Pain of dilation
The “pain” of dilation feels like a pressure in the vagina. It’s also possible to feel aches and discomfort in the back and tingling sensations inside the pelvic area3. It’s very common to hear reports from women who felt absolutely nothing and, upon arriving at the hospital, were already found to have advanced dilation. Therefore, the dilation phase is not the same for everyone’s body.
How to help dilate faster?
In addition to medications such as oxytocin and similar drugs, a woman can do some things to help speed up dilation. Appropriate exercises with a birthing ball help a lot. Also, walking, warm showers for about 1 hour in the shower or bathtub. There are a few other little tricks that can help achieve complete dilation for labor:
Empty your bladder often: holding in urine can interfere with the progress of labor.
Don’t stay lying down: Even if you are in pain, you need to move around. Gravity and movement will help dilation happen. Move your hips: Rotating your hips in circles makes it easier for the baby to descend and consequently for dilation to occur.
Water breaking
If the amniotic sac has ruptured, the safe window for birth is 24 hours without intravenous medication to prevent infection. However, doctors usually don’t let much time pass due to risks to the mother and baby if labor doesn’t occur within this period. If it hasn’t ruptured, the doctor can break it and speed up labor, which will consequently stimulate dilation of the cervix for vaginal birth. Don’t forget that during this time, your baby will be monitored and there will be no greater risks to them. If any intervention is needed, doctors will act accordingly.
See also: What is a Vaginal Birth Like?
