Q: My doctor says that my pelvis may cause a problem during delivery. What kind of problem is he referring to?
A: The size and shape of your pelvis, as well as the size of your baby, impacts your labor and how your baby will be delivered. During labor the baby enters the pelvic inlet, travels through the pelvic cavity, then exits the pelvic outlet into the birth canal.
There are four classifications of pelvises. They are the gynecoid, most common female pelvis shape; the android, the most common male shape; the anthropoid, a long pelvis; and a platypelloid or flat-shaped pelvis.
When we are babies there is no difference between the male and female pelvis. Sexual dimorphism of the pelvis does not take place until puberty.
A female pelvis develops in children that have no gonads. Thus, ovaries and estrogen are not necessary for the formation of the female-type pelvis, but the presence of a testis that is producing androgen is essential for the development of the male pelvis.
The pelvic bones of an adolescent girl grow slower than her other bones. During adolescence the pelvis changes from an anthropoid pelvis to a gynecoid pelvis.
If you are younger than 16, your physician may be concerned that your pelvis has not fully developed. This could complicate your ability to push a baby through your pelvic cavity.
The gynecoid pelvis is round or transversely oval, with adequate diameters for a baby to pass through, wide with a deep curve at the sacrum, with no prominent ishial spines. Perfect for a baby's passage.
The android pelvis is heart shaped, short, has inadequate diameters for a baby to pass through, a flat sacrum that inclines to be long and narrow, and prominent ischial spines. It is difficult for a baby to make the necessary rotations through this shape pelvis, causing the mother to have complications during delivery.
The anthropoid pelvis is long, has an adequate diameter, inclines backwards, has variable ischial spines and has the capacity to allow a baby to travel through.
The labor and delivery for a woman with this pelvis is usually uncomplicated.
However, her baby may be born with the face toward the pubis. This may cause the mother to have a lot pain in her back during labor.
The platypelloid is also called the flat female pelvis. The shape is transverse oval, has both short and long diameters, has a wide deep curve at the sacrum like the gynecoid and also has variable ishcial spines.
The capacity of this shaped pelvis is reduced and women with a pelvis of this shape often have to have Caesarean deliveries.
Variations in the female pelvis and in the planes of any single pelvis are so great that a rigid classification is not possible.
Other factors that might impact the pelvis are previous injuries, bone disease and congenital anomalies of the pelvis.
By identifying potential problems early in your pregnancy, monitoring your progress through the pregnancy, your physician can make the best decisions to help you have a safe delivery and a healthy baby.
Katie Powers, R.N., is a board-certified lactation consultant and perinatal educator at Manatee Memorial Hospital's Family BirthPlace. Her column appears every other week in Health. Contact her at firstname.lastname@example.org.