Cervix dilation is a critical part of labor.
The cervix, which is normally closed to keep the baby safe during pregnancy, now becomes fully dilated to allow the baby to descend through the birth canal.
Imagine your uterus, during pregnancy, as an inflated balloon. You can think of the cervix as the lower part, where you tie the balloon.
Labor contractions help the closed cervix to become a fully dilated opening.
This is the first stage of labor and, as it progresses, you might want to know the signs you’re dilating.
It’s perfectly natural to ask: How do I know if my cervix is opening?
There are several signs of cervix dilation, which some women will notice without the need for an internal cervical check.
Cervix dilation and effacement
Before it can begin to dilate, the cervix must soften and shorten. This is called cervical effacement. If this isn’t your first baby, your cervix might efface and dilate simultaneously.
Cervical dilation is the actual opening of the cervix and it’s measured in centimetres. Dilation is used to determine the different stages of labor.
Your midwife or doctor might offer to perform a cervical check. These findings are usually plotted in a cervix dilation chart alongside with other data, such as frequency of contractions, stage of labor.
As a blind technique, it’s not as important to determine whether the cervix is 5 cm, 6 cm or 7 cm. What’s important to know is whether the cervix is working efficiently.
For a first time mother, it can take up to 2 hours per cm dilated, especially up to 3 cm, depending on many factors – for example, which phase the cervix is at.
Understanding how your body works at each stage of labor should help to assess dilation.
You can opt not to have cervical checks during any stages of labor. Your doctor or midwife, who are at your service, can use other data to assess progress and your health.
Cervix dilation and the stages of labor
Of all the stages of labor, Stage 1 is usually the longest and it’s all about the cervix. Due to contractions, the cervix opens until it reaches 10 centimetres.
Early labor begins with irregular contractions as the cervix starts to change. The length of this stage of labor varies.
Your expectations might play a significant role here, especially if this is your first time having a baby and you’ve passed your due date.
During this phase, the cervix goes from closed to 4 cm dilation.
Active labor has an increasing regularity to it. As labor progresses, women feel the contractions closer together, stronger, and longer-lasting.
In active labor, the cervix will dilate from 4 cm to 10 cm. 10 centimetres means there’s no cervix left.
Then Stage 2 begins and the baby is ready to descend through the birth canal.
Stage 3 finishes with the delivery of the placenta.
9 Signs Your Cervix Is Dilating
Want to know the most common cervix dilation symptoms? Here are 9 signs for you to tell whether your cervix is dilating.
#1: Lightning crotch
Lightning crotch is an unmistakable pain that happens to many women as they get closer to their due date.
The term describes sharp, shooting pains felt in the vagina. The cause? The pressure of your baby’s head as it descends into the pelvis. It pushes on nerves and causes lightning-like shocks.
When cervical dilation begins, it might also cause sharp vaginal pain.
#2: Hello bloody show
Of all the cervix dilation symptoms, this one is very obvious to the eye.
During pregnancy, the cervix forms a seal called the mucus plug. This prevents bacteria from travelling up from the vagina and causing infection.
Discharging a brown or pink-tinged mucus is an early sign of cervix dilation.
Effacement of the cervix causes small blood vessels to break. This causes the mucus to appear as pink or brown.
It’s important to seek medical advice about vaginal bleeding. This is especially the case if:
- You’re earlier than 37 weeks
- The bleeding changes to bright red (not blood-streaked)
- The bleeding becomes pronounced and less mucus accompanies it.
Find out more about the bloody show.
#3: Cramping and backache
Ok, you’re very pregnant with a full-term baby and you’re an expert on cramps and aches.
If they occur low down, just above your pubic bone, this can be a sign your cervix is dilating. It might feel something like the cramping ache you have just before, or at the start of your period.
You might also feel a dull ache in the lower part of your back, which comes at regular intervals.
This can be the start of labor contractions.
#4: Feel your fundus
The basic mechanics of labor are often mixed up in people’s minds.
Most people tend to think of the process as: cervix dilates, uterus contracts, baby is born.
In fact, for the cervix to dilate, the uterus needs to contract first.
Before labor begins, the uterus has a thick layer of muscle which is even all over. When contractions begin, the muscle at the bottom of the uterus is pulled up as the cervix begins to open.
You can read more in What Your Uterus Does During Labour.
The fundus (the top part of your baby bump) thickens as the cervix dilates. You can feel this during a contraction by checking how many fingers you can fit between the fundus and your bra line.
At the beginning of labor, you should be able to fit five fingers in the space.
As your cervix dilates and the baby starts to descend, the fundus will rise and you will fit fewer fingers in the space.
#5: Make some noise
During early labor, you can talk and move about.
Eventually, as your cervix gets more cm dilated you might want to focus, breathe, and move your hips – but certainly not hold a discussion!
Contractions become more intense during this stage, as the cervix becomes more cm dilated.
As labor progresses, you’ll probably feel the need to stop talking and focus on your baby.
It might surprise you how vocal you are during contractions; you might find yourself moaning, singing and roaring, as well as breathing.
Being unaware of what others are doing or saying is also a sign your cervix is dilating further.
The more your cervix dilates, the further you’ll go into this state. When you’re nearing full dilation, you might make new sounds, which are deeper and throatier – yep, that roaring we mentioned earlier.
#6: The purple line
It might sound like an old wives’ tale but the purple line can be used to measure cervical dilation; it’s a method that’s backed by research.
Basically, the purple line is exactly what its name suggests.
As the baby’s head moves down, a reddish-purple or brown line creeps up from the anus to the top of the cleft of the buttocks. It’s present in most women, and the length of the line correlates with cervical dilation.
Due to its placement and the intensity of labor, it might be difficult for women to assess their own purple line, even with the help of a mirror. Your care provider can see it easily, though, and determine the stage you’re in.
We should always take intuition into consideration – especially with regard to our own bodies.
Although intuition is an important aspect of life, we might not pay too much attention to it in many circumstances. Pregnancy, though, is a perfect time to reconnect with ourselves and our babies.
When you wonder whether or not you’re dilating, get in contact with yourself and listen to what your body is saying.
#8: Degree of politeness
You’ll know you’re reaching transition phase, between Stage 1 and Stage 2, when you no longer care about anyone else.
Getting naked, swearing and burping, as though you’re on your own, are definitive signs you’re reaching 10 cm.
The transition phase is usually quite intense and your birth team can offer you plenty of support.
#9: Cervical checks
The easiest way for the doctor or midwife to assess dilation is to do a cervical check. This isn’t necessarily the easiest way for women, especially when they’re in active labor.
It involves lying down on your back and having a care provider insert two fingers into your vagina. This is the way to assess the stage of dilation (how many centimeters) but also the position of the baby.
The cervix is a sphincter that must open to allow your baby to pass through.
It’s affected by your sense of safety and support during labor. The results plotted in the cervix dilation chart can be inconsistent, depending on your emotional state of mind.
Cervical checks are a routine part of hospital maternity care but it doesn’t mean they’re mandatory.
You can read more about this in Are Cervical Checks During Labour Necessary?
Checking your own dilation is possible and, unlike hospital cervical checks, you don’t have to do anything with the information you discover.
For some women, body awareness is empowering. Becoming familiar with your cervix outside pregnancy can help you understand the phase your cervix is in.
You can check regularly to see what ‘normal’ feels like, and what it’s like when cervical dilation starts.
Always wash your hands and keep your fingernails short if you decide to check your own cervix.
To avoid the risk of infection, never insert anything into your vagina if your waters have broken.
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