Imagine inflating a party balloon. As you fill it with air, it becomes larger and rounder, while the neck of the balloon becomes shorter, to the point where it becomes hard to tie it up. Something similar happens to the cervix during pregnancy.
Once labor begins, your cervix will dilate and soften while shortening and becoming thinner (effaced).
The latent phase of labor
At the start of labor, you won’t feel much of anything. It is the latent (or “hidden”) part of labor because while the process has begun, it’s probably flying under your radar. The cervix softens under the influence of hormones (mostly progesterone) and shortens [1].
During the latent phase, the cervix dilates slowly, at a rate of about three to four millimeters per hour. At this pace, it can take up to 20 hours [2] to achieve the dilation needed for birth.
Deciding when to go to the hospital
If you don’t have any risk factors to worry about, you probably don’t have to go to the hospital yet. Instead, take a walk or get some light exercise to coax baby into action. Try to avoid lying down.
When contractions become more frequent (two or three every 10 minutes) and increase in pain, or when your water breaks, you’ve crossed into the active phase of labor, and it’s time to go to the hospital. Your cervix is probably around six centimeters (2.3 inches) dilated, and the rate will jump to around 12 to 15 millimeters per hour [2].
Slow or halted dilation
While uncommon, the cervix may dilate more slowly or stop dilating altogether during labor. That can be due to a variety of causes, including epidural anesthesia, which can reduce the production of or your sensitivity to oxytocin, an essential hormone for cervical dilation [3]. When this happens, your doctor may temporarily take a wait-and-see approach for a couple of hours. If the cervix does not dilate further, you may receive oxytocin to speed up labor. Another strategy is to pierce the amniotic sac (amniotomy) if your water has not yet broken, which can encourage cervical dilation. According to the Cleveland Clinic, healthcare providers have mixed feelings about the benefits of amniotomy. Some studies show it can shorten labor by about an hour. Other evidence shows that intervening with labor isn’t effective [5]. Your doctor will decide whether it's needed according to your situation and labor progression.
The most important factors to monitor during this wait time are the baby’s heartbeat and the mom’s overall condition. If there are no causes for concern, you can probably wait for your cervix to dilate without intervention [4]. It’s important to communicate with your doctor and to voice your concerns and desires regarding decisions about your care during labor.
