What are some reasons for an "unplanned C-Section" during a planned normal vaginal delivery?
ANS: The most common reason is "Failure to Progress". Some other reasons include fetal distress, multiple births, premature births, positioning of the baby, pelvis issues, or complications during pregnancy. I will now discuss each reason breifly.
In order for a natural labor to occur, three factors must be achieved. There must be strong enough contractions to dilate the cervix to ten centimeters, the fetus must be able to transcend through the birth canal, and the pelvis must be large enough to allow the baby to make the trip down the birth canal. If these three factors do not occur, then it is called "failure to progress."
If the baby's heart rate slows or accelerates too quickly or shows no signs of activity, most often he is considered to be showing signs of "fetal distress".
If the baby is in an unfavorable position for delivery, a C-Section may be needed. Breech(feet first) position, or Transverse(sideways) position are not ideal positions for vaginal delivery.
Pelvis issues mean that the mother's pelvis must be large enough for baby to make the trip down the birth canal. One particular pelvis issue is called "Platypelloid Pelvis" which occurs in about 4% of women. The Platypelloid Pelvis' shape is very flat, narrow, and can not allow most normal sized babies to pass through.
Complications during pregnancy may cause need for a C-Section. If a mother develops a complication such as toxemia, also known as preeclampsia, then it is highly likely that she will have to have a C-section before her expected due date.
Lastly, C-Sections are done when there is an emergency situation. Situations could be prolapsed umbilical cord, placenta abrutio, placenta previa, and fetal distress.
That pretty much covers the most common reasons for C-Sections. Keep in mind that 20% of births are done by C-Section. My C-Section was done because of Platypelloid Pelvis. Also, in my Lamaze Class there were six couples total. At our class reunion after the birth of our babies all six couples ended up with unplanned C-Sections! So never say an unplanned C-Section won't happen to you!