Cephalo-Pelvic Disproportion

“Cephalo-” means head, and refers to the fetus’s head. CPD refers to a fetal head which is too big to fit through the mother’s pelvic bones. Cases of true CPD will not result in vaginal birth. Borderline cases of CPD may allow the head to emerge (after “molding”) only to have the shoulders become stuck above the mother’s pubic bone (a condition called “shoulder dystocia”).

True CPD is actually relatively rare, though it (like FTP) is often criticized as a poor excuse to resort too quickly to c-section. Many women who have had the diagnosis of CPD as the reason for a c-section often will deliver larger babies vaginally in subsequent pregnancies.

CPD is more common in conditions in which big babies are produced, like gestational diabetes. Unfortunately, there is no accurate way in 1999 to diagnosis CPD with high degree of accuracy. The weight of the baby (fetal weight) can be “estmated” by a doctor or midwife by physical examination or ultrasound. Neither method is very accurate.

At some point a case of true CPD will become a labor with a case of true FTP. It just won’t fit through. After a period of patience and a period of intervention (often, the use of Pitocin to increase the strength of the contractions), only a c-section will get the baby delivered.

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