Cephalopelvic Disproportion: What You Should Know

woman leaning over couch during labor

You may ask, “Cef-alo-pelvic what?” upon hearing about this medical condition for the first time. The term “cephalopelvic disproportion” (CPD) is a situation in which a baby’s head won’t fit through the mother’s pelvis during birth because the infant’s head is too big for the birth canal.

CPD is infrequent, according to the American Pregnancy Association. Many mothers whose labor process is labeled as “failure to progress” are often given a diagnosis of CPD, even when it isn't technically CPD. However, when it’s actually CPD, the recommended safest kind of delivery would be a cesarean section.

Causes CPD

Some risk factors for CPD may include:

  • Bigger baby size—related to:

    • Diabetes (or Gestational Diabetes)

    • Genetics

    • Longer pregnancy (due date has passed)

    • Multiple pregnancies

  • Mother has a small or irregularly shaped pelvis

  • The expectant mom is age 35+

  • Unusual position of the fetus

newborn sleeping

How to Know if You Have CPD

What if you don’t know that you have this problem until you’re already feeling birth pangs? In most cases, CPD is not diagnosed before the labor process starts—even if the baby is considered large, and the mom’s pelvis is smaller than average.

When the rhythmic labor contractions begin in muscles at the top of the uterus, they continue downward as labor progresses. The labor contractions typically push the baby’s head against the cervix—which initiates even stronger contractions. As labor continues, the abdominal wall muscles contract; this helps to force the baby through the cervix and vagina. During this process, the baby’s head shape adjusts slightly and the mother’s pelvis joints spread apart to allow more space for the baby to go through the pelvis. But if those joints don’t widen to let the baby’s head get through it, you may have true CPD.

Who Is More Likely To Have This Disproportion?

Take comfort in the fact that CPD only happens in one of 250 pregnancies, according to the American College of Nurse Midwives (ACNM). If your doctor suspects or diagnoses you with CPD, this shouldn't necessarily cause concern for future pregnancies. Studies show that more than 65 percent of women diagnosed with CPD in previous pregnancies could deliver vaginally in their subsequent pregnancies.

baby in bathroom after a bath

Can CPD Be Detected in Advance?

While ultrasound is used to figure out possible fetal size in advance, it’s not completely reliable. Plus, ultrasound testing can’t yet estimate the actual weight of your growing baby. Your doctor can do a physical exam to measure your pelvic size, and this may help to determine whether you would be at risk for CPD. If it still isn’t possible to diagnose CPD and you are concerned you might have it, ask your doctor about solutions other than a cesarean.

If you and your doctor agree that your risk for CPD is low, then you can work together with your midwife or doula to plan for a vaginal delivery.

The medical team, midwife, or doula can help with changing the baby’s position within the pelvis during the birthing process. Some physicians also prescribe medication to help speed up the labor process.

Issues That Can Result from CPD

Some malpractice attorneys warn expectant mothers about common mistakes obstetricians have made in some cases when dealing with possible CPD:

Overuse of Pitocin. One of the main issues with CPD is that the obstetrician, in an effort to speed up the labor process, might give the birthing mother too much Pitocin (a chemical form of the natural hormone oxytocin). Overuse of such labor-inducing drugs may cause traumatic contractions, thus hurting the baby.

Excessive Labor. On the other hand, some doctors might let labor go on for an unnecessarily long period. Such extended labor may cause the baby distress or possibly result in oxygen deprivation. These injuries may become the precursor to delays in development.

Physical Injuries. If you have CPD and deliver vaginally, the baby may have a higher chance of getting injuries, such as shoulder dystocia (shoulders fail to clear the vaginal opening during birth) or oxygen deprivation.

Childbirth Options with CPD

Of course, CPD is a reality for some women and a cesarean would be the best course of action in those cases. Yet, the occurrence of CPD is rare. It may not really be necessary to interfere with the normal birth process. So, if you were dreaming of natural vaginal birth, there is hope.

Carry on that hope by educating yourself fully on natural childbirth and CPD. By doing this and seeking the guidance of your doctor and midwife or doula, you will be better equipped to make an informed decision if the need arises. You may be able to have your first and subsequent babies naturally after all!