Cephalopelvic disproportion
Cephalopelvic
disproportion occurs when the baby's head or body is too large to fit in the
mother's pelvis. Genuine head-pelvic disproportion is thought to be rare, but
many cases of "delayed progression" during labor are diagnosed with
head-pelvic disproportion. With an accurate diagnosis of head-pelvic
disproportion, the safest type of delivery for the mother and child is
caesarean section.
What causes cephalopelvic disproportion?
- Large child due to:
- hereditary factors
- Diabetes
- Postmaturity (still pregnant after the due date has passed)
- Multiparity (not the first pregnancy)
- Abnormal fetal positions
- Small pelvis
- Abnormally shaped pelvis
How is cephalopelvic
disproportion diagnosed?
The diagnosis of
pelvis-head disproportion is often made when labor activity is insufficient and
medical treatment, such as the use of oxytocin, has failed or has not been
attempted. Cephalopelvic disproportion can rarely be diagnosed before labor
begins if the baby is considered large or if the mother's pelvis is known to be
small.
During birth, the
baby's head takes shape and the pelvic joints straighten out, creating more
room for the baby to cross the pelvis.
Ultrasound is used to
estimate fetal size, but is not completely reliable in determining fetal
weight. A physical examination, in which the size of the pelvis is measured,
can often be the most accurate method for diagnosing cephalopelvic
disproportion. If a true diagnosis of pelvic disproportion cannot be made,
oxytocin is often administered to speed up labor. Alternatively, the position
of the fetus changes.
What about future pregnancies?
Cephalopelvic
disproportion is rare. Head-pelvic disproportion occurs in 1 out of 250
pregnancies. If you have been diagnosed with head-pelvic disproportion, this
does not mean that you will have this problem in future births.
More than 65% of women diagnosed with head-pelvic disproportion during previous pregnancies were able to give birth through the natural birth canal in subsequent pregnancies.