© 2010, Carol Peterson, ICCE, CD(DONA) Erie, PA

Birth Journeys

Carol Peterson, ICCE, HCHI, CD(DONA)

Instilling Confidence in Birth Since 2004

814-899-7722  * cbecarol@yahoo.com

 

 

Baby Too Big For Pelvis: The Truth About Cephalopelvic Disproportion

 

January 2008 Newsletter, by Carol Peterson, ICCE, CD(DONA)

 

Have you, or someone you know, been told that a cesarean occurred due to CPD, or cephalopelvic disproportion?  Do you really know what this term means?  And, how will it affect future labors?  The true definition of CPD is when a baby's head or body is too large to fit through mom's pelvis.  It is believed that this occurrence is rare, but a large number of labors that are deemed "failure to progress" are labeled as probable CPD.  When an accurate case of CPD is found, the safest way for baby to be born is via cesarean; however, CPD is not something that can be easily determined without a trial of labor.

 

What causes CPD?

 

There are several reasons why a labor does not progress past a certain dilation, even when adequate time is given.  Under these circumstances, it is possible for a caregiver to use the term cephalopelvic disproportion.  While the true definition is when baby is too big for the pelvis, these other factors may also lead to a diagnosis of CPD:

Odd fetal position.  The ideal way for a baby to enter the pelvis is with the chin tucked, so that the narrowest part of the head enters the pelvis.  However, some babies enter without their chins tucked, which can create a labor that is slower as it takes longer for baby to move through the pelvis.  While some babies will not be able to navigate the pelvis in an odd position, many still can.  It is even possible for some babies to be born with a face presentation, when the baby's head is tipped back, as though she is looking into the pelvis.

 

In the case of odd fetal position, some medical providers will give up too soon and perform a cesarean.  Many doctors follow a 1 cm dilation per hour rule, which rarely holds true for any labor.  Given time, many women are still able to give birth vaginally.  I have even seen a midwife gently reposition a baby's head once mom was fully dilated, which allowed mom to give birth vaginally.  

 

Small or odd-shaped pelvis.  Again, there is no way to tell in a first labor if this will pose a problem.  Molding of the unborn baby's head combined with flexing of the pelvis may allow passage of the baby.  The actual number of women with a too small or abnormally shaped pelvis is quite small.

 

Does this mean that I should just have a cesarean if my baby is big?  I am very petite or have been told I have a small pelvis... shouldn't I just have a cesarean?

 

No!!!  Ultrasounds can be wrong, and any type of pelvic measurement or x-ray will not take into account the ability of a pelvis to spread.  Also, a person's size in no way determines her ability to birth.  Even tiny women can give birth to 10 pound babies.  I personally know of several girls that are very petite and had 9 and 10 pound babies.   While cesareans are safer today than in years past, they are still not safer than vaginal deliveries in the majority of circumstances.

 

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