Understanding Cervical Effacement & Baby’s Head Position

| Reviewed By Amanda Lundberg, BSN, RN

During the third trimester of your pregnancy, your obstetrician may ask for your permission to begin conducting cervical exams.

Cervical exams check for cervical position, effacement, dilation, and the baby’s station.

The medical terminology involved can make this a confusing and anxious time for new mothers, especially when the doctor mentions feeling the baby’s head!

If the doctor can feel the baby’s head, am I effaced? If the doctor can feel the baby’s head, effacement has occurred to some degree, which is determined by cervical exam. The distance between the cervical membrane and the bottom of the cervical wall is measured in percentages. 100% means that the cervical membrane is paper thin and ready for delivery.

Understanding the terminology your obstetrician uses in the third trimester can help reduce anxiety regarding labor and delivery. Keep reading to learn more about how the cervix changes during pregnancy and what that means for you. 

Cervical Effacement Explained

In pregnancy, the cervix both protects against infection from outside sources and prevents your baby from descending. It’s located between your uterus, where the baby is growing, and your vaginal canal, which the baby is delivered through.

In preparation for labor, the cervix goes through a series of changes. But what are these changes, what do they mean, and when do they occur? 

What Is Effacement?

Effacement is the thinning and shortening of the cervix prior to childbirth. Effacement occurs as a result of contractions in early labor and is measured in percentages.

At the beginning of pregnancy, the cervix starts out long and thick. By the end of it, the cervix will be short and paper thin.

During labor, the remainder of the cervix pulls back over the baby’s head, and it’s only a matter of time before your little human is out in the world. 

When Does Effacement Start?

Cervical effacement typically starts within a few weeks of labor. However, every pregnancy is different, and it may begin earlier or later in some cases.

Your obstetrician typically won’t start checking for effacement until 36 weeks or later. 

How Long Does Effacement Take?

Unfortunately, there is no definitive timeline in which effacement takes place. Once the process has started, it could be hours, days, or weeks until 100% effacement is reached. Most of the time it’s the latter.

There are ways to assist in effacement, thereby shortening the amount of time it takes, but many are only anecdotally supported. 

Effacement vs. Dilation

When talking about effacement vs. dilation, it helps to visualize the cervix.

Your cervix is composed of a thick, circular wall with an opening in the center that leads from the vaginal canal into the uterus. During pregnancy, this opening is filled with mucus, also known as the mucus plug. 

An illustration depicting the early stages of effacement and dilation.

Effacement is when the wall of the cervix begins to thin, soften, and shorten, thus becoming more malleable. Keep in mind that the cervical wall is what holds the mucus plug in place.

Once effacement begins, the mucus plug becomes looser until it eventually falls out and is excreted from the body. Effacement must be at 100% to vaginally deliver a baby. 

On the other hand, dilation is when that small opening in the center of the cervix gradually grows into a larger opening. Much like effacement, dilation is also a direct result of contractions and also contributes to the loss of the mucus plug.

However, dilation is measured in centimeters, not by percentages. The cervix must be dilated to 10 cm to vaginally deliver a baby.

Both processes aid in unblocking the path between the uterus and vaginal canal, and both must be completed to vaginally deliver a baby.

How To Measure Cervical Effacement

Cervical effacement is measured in percentages. The process by which this measurement is taken involves vaginal penetration. For this reason, you can always deny a cervical examination if you are not comfortable.

Obstetricians learn to measure effacement by where on their finger the cervix ends. This means that it’s best to have the same person measure each time.

The cervix starts out between 3 and 4 cm thick. This means that when the doctor’s finger enters the cervical opening, the cervical wall will reach just above the first knuckle. This is 0-10% effacement.

As softening continues, the cervical wall will cover less of the finger until it becomes paper thin.

Does Effacement Predict Labor?

While effacement doesn’t give you a countdown to when active labor will begin, it does indicate that you’re in early labor. Early labor is the first phase of the first stage of labor.

This phase can last hours, days, or weeks depending on physical factors and how many children you’ve birthed. 

How To Efface Cervix Faster

There are ways that we can help our bodies along during early labor. However, it should be noted that most of these methods are only anecdotal, meaning that there are not sufficient studies that conclusively prove that these methods effective.

Sex

Male semen contains prostaglandins, hormone-like compounds that are thought to ripen the cervix.

In addition, the female orgasm causes uterine contractions. Since contractions are the driving force behind dilation and effacement, it is logical to assume that sex helps kick start labor. 

There are certain instances in which you may want to refrain from sexual activity.

Due to an increased risk of infection, especially in those with Group B Strep, it’s best to contact your doctor for a consultation if you wish to have sex after you’ve lost your mucus plug.

It’s also strongly advised not to have sex if your water is leaking or broken or you are experiencing placenta previa. 

Gravity

Gravity is your best friend when it comes to natural means of effacing and dilating your cervix.

Walking, curb walking, and using a birthing ball all utilize gravity by encouraging the baby to push against the cervix. It can also help by increasing blood flow, which can encourage cervical changes. 

Can You Be 100% Effaced and Not in Labor?

This depends on if you’re talking about labor as a whole with all of its stages and phases or if you’re just talking about active labor.

Effacement occurs in the first phase of the first stage of labor called early labor. At this point, your body has started preparing for your baby’s arrival by beginning contractions, effacement, and dilation. So, you are always in labor when effacing. 

However, you’re not always in active labor. Active labor is what most women think of when they envision having their baby. It’s possible to be fully effaced but not be in active labor. 

When Can the Doctor Feel the Baby’s Head?

Whether or not a doctor can feel the baby’s head has to do with fetal stationing. Fetal stationing is a measure of how far the baby’s head has descended into the pelvis.

So long as the baby is head down, an obstetrician can usually feel the baby’s head and determine station between 34 and 38 weeks when they may begin cervical exams. 

Every pregnancy is different though, and variations in this timeline are normal. If you’re concerned about your baby’s position, reach out to your obstetrician. 

What Does Engaging Mean in Pregnancy?

When a baby’s head is engaged, it means that the widest part of their head has descended into the pelvis. This is also sometimes referred to as lightening.

Fully Engaged Baby

A baby is fully engaged when the head is at station 0 at the bottom of the pelvis. This means that the baby’s head is aligned with the ischial spines.

At this point, the baby is correctly positioned and ready for labor. Full engagement may occur weeks before labor or while it’s happening.

What Does It Feel Like When Baby Drops?

When your baby drops, it will likely be noticeable. Not only does your bump appear to rest lower, but it will feel lower as well. The pressure on your lungs and chest will subside. 

Meanwhile, pressure will increase in your pelvic region and against your bladder. Most women report more frequent urination, shooting pains, and discomfort while walking. 

Stations During Labor

When obstetricians refer to a baby’s station, they’re talking about how far into the pelvis the baby has descended. 

Stations are measured on a spectrum of -5 to +5. Each interval is indicative of 1 centimeter of descent.

Negative numbers represent how many centimeters above the ischial spines the baby’s head is, whereas positive numbers show how far past the ischial spines the baby’s head is. 

  • -5 means that the baby’s head is 5 cm above the ischial spines. At this point, the baby is “floating” and will often move away from the fingers. 
  • -4 means that the baby’s head is 4 cm above the ischial spines.
  • -3 means that the baby’s head is 3 cm above the ischial spines.
  • -2 means that the baby’s head is 2 cm above the ischial spines.
  • -1 means that the baby’s head is 1cm above the ischial spines. 
  • 0 means that the baby’s head is fully engaged in the pelvis. At this point, the head is even with the ischial spines. 
  • +1 means that the baby’s head is 1 cm below the ischial spines.
  • +2 means that the baby’s head is 2 cm below the ischial spines.
  • +3 means that the baby’s head is 3 cm below the ischial spines. This is when the baby’s head is crowning. 
  • +4 means that the baby’s head is 4 cm below the ischial spines.
  • +5 means that the baby’s head is 5 cm below the ischial spines.

Labor Progression

A supportive husband offering his wife encouragement during labor and delivery.

Every pregnancy is unique in its timing, but there’s a general progression to labor that’s similar across the board.

Labor can be broken down into three stages. Some stages are composed of multiple phases. We’ve put together a brief synopsis of how labor progresses and what these stages look like.

Stage One: Labor

The first stage of labor contains three phases – early labor, active labor, and transition.

Phase One: Early Labor

Early labor occurs as your body is dilating from 0-4 centimeters. It typically lasts anywhere from 8-12 hours, but in some cases can be longer or shorter.

During this time, contractions are usually mild and manageable, occurring every 5-30 minutes and lasting 30-44 seconds. These contractions may feel like lower back aches, menstrual cramps, or tightening in the pelvic area. 

The best thing to do during this phase is to relax. Eat light snacks, drink plenty of water, prepare for the hospital, and sleep if you can manage it.

Phase Two: Active Labor

Active labor occurs as your body is dilating from 4-7 centimeters. It typically lasts anywhere from 3-5 hours, but labor could slow down if pain management is administered or if this is the first child.

During this time, contractions are 3-5 minutes apart and 45-60 seconds in duration. These contractions are usually increasing in strength, duration, and frequency.

You should go to the hospital when your contractions reach intervals of 5-1-1.

This is when contractions come five minutes apart, for one minute apiece, having occurred for at least one hour. This is the time period in which you’d receive an epidural.

Phase Three: Transition

Transition occurs as your body dilates from 7-10 centimeters. This typically lasts anywhere from 30 minutes to 2 hours. During this time, contractions will occur every 1-2 minutes and last 60-90 seconds.

Contractions during this stage are intense and can cause a plethora of other symptoms such as nausea, vomiting, gas, cold sweats, and hot flashes.

At this point, your body is in the home stretch. If you’re going medication-free, this is going to be the hardest phase of labor as the contractions peak.

This is usually the most strenuous part of labor as the demands of your body are reaching the peak of childbirth.

Stage Two: Childbirth

When you reach 10 centimeters dilation and 100% effacement, it’s time to deliver your baby. This can take anywhere from a few minutes of pushing to a few hours. By this point, your baby’s head begins to show and is crowning at the +3 station. 

Your care team will assist you with knowing when to bear down and push and guiding your baby out of the vaginal canal.

You’ll push during your contractions and rest between them. This process may take longer for first-time moms or those who’ve gotten an epidural.

Stage Three: Afterbirth

The last stage is the delivery of the placenta. This is typically the shortest part, lasting less than a half hour.

You’ll continue to have contractions during this time as your body separates the placenta from the uterine wall. The placenta will then make its way into the birth canal. 

At this point, the doctor will typically use the umbilical cord to guide the placenta out. At times, they may put pressure on your abdomen to help facilitate this process and make sure the placenta comes out in one piece.

Related Questions:

70% Effaced – How Much Longer?

A cervix that is 70% effaced only has 30% of the way to go before it is thin enough for labor. Effacement can take several hours or even days. Every pregnancy is different, and effacement could happen quicker or slower in some situations. 

What Does It Mean When the Baby Drops?

When the baby drops, it means that they’ve lowered themselves into the pelvis. At this point, they’re getting into the appropriate position for birth.

This milestone leads to many physical changes such as increased urination, reduced pressure to the lungs, a lower appearance of the bump, and more pressure to the pelvis. 

Conclusion

Cervical effacement is the thinning and shortening of the cervix in preparation for birth. It is measured in percentages, and a woman must reach 100% prior to vaginal delivery.

The duration of this process differs from pregnancy to pregnancy, but there are ways you can help it along.