Understanding CPD Associated With Big Baby And Small Pelvis

As your pregnancy belly expands many people start worrying unnecessarily about you giving a normal birth. ‘That belly is huge’, ‘You will have a big baby’, ‘I think doctors will recommend a cesarean’. All these comments that come along your pregnancy journey. The trick is to brush it off.

It is good to ignore them because we know the incredible body given to us is capable of birthing perfectly well. So how far are these claims about small pelvic and larger baby true?


The truth is in the rarest of rarity such a condition exists where the baby’s head or body is big and cannot fit through the gap in the mother’s pelvis. In cases, when the labor isn’t proceeding, it is termed as Cephalopelvic disproportion (CPD), though there could be other factors playing a greater role in the delivery. In CPD, medical therapies and administration of oxytocin to quicken the labor fail to have much effect.

Most doctors go for a cesarean after the diagnoses of the condition.


Previously during 1700 and 1800, cases of women with pelvic deformities due to a widespread and incurable condition like polio did exist. CPD was a common outcome, which also resulted in the fetal mortality in one or two cases. With the advancements in science and an adoption to a better lifestyle, the number of such cases has decreased.

Conditions that still arise are due to the abnormalities of the pelvis or pelvic injuries. The risk increases if—the age of mother is above 35, she has diabetes or gestational diabetes, pregnancy is over due-date or the baby is big. Sometimes bruising and flexing of babies head also make the labor hard and is misdiagnosed as CPD.


Most cases that come to light today aren’t diagnosed properly. CPD can not be known until labor stars and proceeds. So mothers mustn’t fret if they tell you your baby is too big to fit through your pelvis even before the labor starts.

Understanding How The Labor Progresses

Your bay’s position determines your ease of labor. If they are not in an optimal position of birth—the back of their head is against the back of your pelvis (posterior position) or they are in breech position, you have a higher chances of having a c-section. Sometimes, if the labor doesn’t progress, the mothers are diagnosed with CPD without taking into account the position of the baby before birth.


Labor doesn’t involve your sole hard work. Your baby also twists and turns and thus helping itself to wriggle out of the birth canal. The bones of their skull aren’t fused together—their head molds and undergo subtle changes in shape to fit through the birth canal as they move down.

Similarly, your pelvis isn’t fixed either. It is made of many bones that are attached to each other through joints and ligaments. Since your body releases a hormone called relaxin, it helps your joints to loosen up—the reason moms complain of pain in the last months of pregnancy. This loosening of joints and ligaments creates a space for your baby to descend during labor.


While this happens, your position if birth also matters. Some positions constrict the space for movement—the usual reclining on the bed that is followed in most hospitals is one such position. Women who try different positions of birth like squatting or side-lying or going on all fours can create more space for the baby to move out.

All the factors come into play when you are pushing your baby out irrespective of the size of the baby.


Can CPD Occur Again?

It is considered a rare condition and a recurring CPD is even rarer. A study published the American Journal of Public Health stated that more than 65% of women who experienced CPD in previous pregnancies had normal deliveries later on.

It also depends upon why the previous pregnancy was a CPD. If there was a congenital abnormality of pelvis or a serious injury, it may occur again. Moms are advised to consult your doctor to find the reason CPD was diagnosed previously. If you aren’t satisfied, go for a second opinion—you as a mother must seek all the information associated with it.


Understand Your Pregnancy

  • Moms must know the causes behind a halted labor—it could be your baby’s positioning or even your positioning during labor.
  • Ask your obstetrician or midwife more about CPD—when is it detected, what procedures do they follow in such a case, and whether it can occur again. This will give you a clearer picture of your doctors approach.
  • Read about instances where the mother was diagnosed with CPD, yet had normal subsequent deliveries.
  • Hire a doula during your birth, ask about various positions of birthing that can avoid CPD, rather a wrong diagnosis of CPD.
  • Know your body. Attend childbirth education class that help you prepare for labor and birth, and help you understand the capabilities of your body.

You could have found out through an ultrasound that you are having a big baby. However, there is no way to determine accurate birth weight of the baby before they are born.

Even if your baby may appear big in the ultrasounds or macrosomia is detected, remember that CPD cannot be predicted until birth.