Cephalopelvic Disproportion

Cephalopelvic disproportion is a rare childbirth complication. It occurs when your baby’s head doesn’t fit through the opening of your pelvis. It’s more likely to happen with babies that are large or out of position when entering the birth canal. The shape of your pelvis can also be a factor.


What is cephalopelvic disproportion?

This condition occurs when your baby’s head doesn’t clear the opening of your pelvis during childbirth.

Cephalopelvic disproportion is a rare complication that can stall delivery. A skilled birth attendant (midwife, obstetrician or another healthcare provider) must then step in to assist.


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Why might a baby not fit through the pelvis during delivery?

There are many reasons:

  • Your baby’s head may be too large.
  • Your baby may not be in the proper position. They may be facing sideways or outward when entering the pelvis.
  • You may have a small or abnormally shaped pelvis.

What happens with a typical birth?

Weeks before labor, babies get into position. This occurs when your baby drops into your lower pelvis.

When a baby drops, usually their:

  • Head is pointed down.
  • Face is toward your back.
  • Chin is tucked into their chest.

During labor:

  • Your baby’s head enters your pelvic opening.
  • Pressure from your baby’s head causes your pelvic joints to spread, creating a wider opening.
  • Your baby’s body rotates so that their shoulders can squeeze through your pelvis.
  • Contractions ease your baby down the birth canal.
  • Your baby is born after exiting the birth canal through the exterior opening of your vagina.

How common is cephalopelvic disproportion?

The condition is fairly rare, occurring in 1 out of every 250 births.

Symptoms and Causes

What causes cephalopelvic disproportion?

Many conditions and circumstances can lead to cephalopelvic disproportion.

Baby size

There are several reasons that a baby may be too large. These include:

  • Being past their due date.
  • Excessive maternal weight gain during pregnancy.
  • Family history of large babies.
  • Conditions in the birthing parent like diabetes or gestational diabetes.
  • Multiparity, meaning that you’ve given birth at least one time before.
  • Biological parents have obesity (a BMI greater than 30) or overweight (a BMI greater than 25).

Birthing parent’s pelvis

Your baby might not fit through your pelvis if the opening is too small. Conditions and circumstances that may cause this include:

  • Birthing in adolescence, when your pelvis isn’t skeletally mature.
  • Pelvic malformations that may cause bony growths affecting the opening. Malformations may also result in bones that are out of place.
  • Petite birthing parent whose pelvic opening is too small.
  • Previous trauma, such as a fractured pelvis. This can make it difficult for the joints to spread.


Can pelvic shape raise the risk of cephalopelvic disproportion?

Some pelvic shapes have narrow openings that make it challenging for a baby to pass through.

Cephalopelvic disproportion is more likely to happen with a:

  • Flat (platypelloid) pelvic opening: A person with this type of pelvis has an oval opening that’s wide from side to side but narrow from top to bottom.
  • Heart-shaped (android) pelvis: The pelvic opening is wide on top and narrows toward the bottom.

When does cephalopelvic disproportion happen?

Cephalopelvic disproportion occurs during the early stages of labor. It’s likely to occur during the active phase when a baby descends the birth canal.


What are the signs and symptoms of cephalopelvic disproportion?

Healthcare providers may suspect cephalopelvic disproportion when there’s failure to progress. This situation occurs when labor takes longer than expected. It can occur for a variety of reasons, including cephalopelvic disproportion.

Failure to progress is likely when:

  • You’re in labor for the first time and it lasts 20 hours or longer.
  • You’ve previously given birth and labor lasts for 14 hours or more.

Additional signs of failure to progress include:

  • Your baby’s head isn’t moving toward the pelvic opening.
  • Contractions aren’t strong enough to move your baby along the birth canal.
  • Slow or no thinning or dilation of your cervix.

Diagnosis and Tests

How is cephalopelvic disproportion diagnosed?

It’s rarely diagnosed before labor. If labor fails to progress, skilled birth attendants determine whether it’s due to cephalopelvic disproportion.

This may involve:

  • Applying pressure to your abdomen to determine your baby’s position.
  • Checking your cervix to see whether it’s opening as it should.
  • Using a fetal monitor to assess contraction history.

Can cephalopelvic disproportion be diagnosed before labor?

During routine check-ups, healthcare providers use prenatal ultrasound to measure fetal growth. Ultrasound can also measure your pelvic opening. However, these measurements aren’t always accurate, making it challenging to diagnose cephalopelvic disproportion before labor.

Management and Treatment

How is cephalopelvic disproportion treated?

Treatment may involve various assisted delivery techniques, such as:

What are the complications of cephalopelvic disproportion?

Complications affecting you or your baby can occur if there’s a vaginal delivery:

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Is it possible to prevent cephalopelvic disproportion?

It’s not always possible to prevent cephalopelvic disproportion. People who have risk factors don’t always have complicated births. A successful vaginal delivery may still be possible even if your baby measures large or you have pelvic issues.

Identifying risk factors early enables healthcare providers to discuss safe delivery options with you before you go into labor.

Outlook / Prognosis

Can cephalopelvic disproportion affect your baby after birth?

This condition typically doesn’t affect your baby’s well-being after birth.

Living With

If I had cephalopelvic disproportion with a previous pregnancy, am I likely to experience it again?

Previous cephalopelvic disproportion doesn’t always mean you’ll experience it in the future. Many people have successful vaginal births with future pregnancies. People with small pelvic openings or a history of large babies are more likely to experience cephalopelvic disproportion again.

A note from Cleveland Clinic

Cephalopelvic disproportion is a childbirth complication. It happens when your baby can’t pass through the opening in your pelvis. There are many reasons it can occur, including a large baby or pelvic irregularities. Cephalopelvic disproportion rarely affects the long-term well-being of you or your baby.

Medically Reviewed

Last reviewed on 11/22/2022.

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