Babies often twist and move around inside their mothers' uterus during pregnancy. A few weeks before the mother's due date however, most babies settle into a position that allows them to be delivered head first. If the baby is not in the correct position before delivery, it can complicate labor and cause injury to the baby. A doctor will try to move the baby into the correct position and, if that fails, might decide to do a cesarean section rather than attempt a vaginal birth.
In preparation for birth, most babies settle into a position in which their heads point toward the birth canal and their feet are at the top of the uterus. This allows them to be born head-first. The most common delivery position is the occiput anterior position, in which the baby's face is facing the mother's back. This position is the most preferable because the smallest part of the baby's head makes its way through the birth canal first. If the baby's face is facing toward the mother's abdomen, it is in the occiput posterior position. A baby in the occiput posterior position can make delivery longer and more painful because the baby has a more difficult time extending her head past the public bone. Most babies in the occiput posterior position turn themselves around during labor. If that does not happen, the doctor might rotate the baby around manually.
Most babies move into the delivery position a few weeks before birth. A few weeks before the due date, the doctor might place her hands on the mother's belly to determine where the baby's head, buttocks and legs are. If the doctor feels that the baby is not in the correct head-first position, an ultrasound or X-rays will be used to determine the baby's position. Positions other than head first are called breech positions.
Some of the most common breech positions are the frank breech, complete breech and footling breech. The frank breech is when the baby's buttocks face the birth canal while the head and legs are near the top of the uterus. A complete breech means that the baby's buttocks and legs, folded at the knees, are at the bottom of the uterus. A footling breech is when one or both of the baby's feet will come out first. It is not known why some babies fail to move into the correct position a few weeks before delivery, although it is more common in women where the uterus has too little or too much amniotic fluid, the uterus is abnormal or the placenta is situated low in the uterus. Breech positions are also more common with twins, subsequent pregnancies and when there is a history of premature births.
Vaginal delivery of a baby in a breech position increases the risk of injury to the baby since the umbilical cord can get squeezed as the baby goes through the birth canal, reducing the baby's supply of blood and oxygen. Also, the birth canal may not had enough time to expand wide enough for the head. The best time for a doctor to turn the baby into the proper position is between 32 and 37 weeks of pregnancy. A variety of medical and natural techniques, including gentle pushing, relaxing the uterus through chiropractic care and playing noise on the lower abdomen to attract the baby to move, can be used to encourage proper positioning. If the baby is still in a breech position when labor begins, the doctor will decide whether a vaginal birth or cesarean section should be done. Factors that the doctor will consider are the baby's breech position, the baby's size and term and if the baby shows any signs of distress.