Approximately 4 percent of babies present in the breech position when labor begins. In this presentation, the baby's bottom is the presenting part instead of the head, which is called a vertex presentation. Using a technique called a version, an obstetrician may attempt to turn the baby to a head down position. This is only successful approximately half the time, and there are possible complications with the procedure, such as umbilical cord entanglement and separation of the placenta. However, some practitioners are very successful with versions, and it does make a vaginal delivery safer.
The risks of vaginal delivery with breech presentation are much higher than with a head-first (vertex) presentation. The mother and attending practitioner need to weigh the risks to make a decision on whether to deliver via a cesarean section or attempt a vaginal birth. The degree of risk depends to a great extent on which one of the three types of breech presentations it is. In a frank breech the baby's legs are folded up against its body. This is the most common breech presentation and the safest for vaginal delivery. The others include complete breech, in which the baby's legs are crossed under and in front of the body, and footling breech, in which one leg or both legs are positioned to enter the birth canal. Neither of these is considered safe enough for a vaginal delivery.
Even with a complete breech, there are other factors to consider for a vaginal birth. An ultrasound examination should be done to determine that the baby's head is not too large and that it is tilted forward (flexed) rather than back (hyperextended). Fetal monitoring and close observation of the progress of labor are also important. A slowing of labor or any indication of difficulty in the body passing through the pelvis should be an indication that it is safer to consider a cesarean section.