Breech Birth And Other Positions
In the last weeks of most pregnancies, your baby will be head-down in your uterus. A small percentage of babies assume different positions, some of which make vaginal birth risky and require surgical intervention if the baby does not turn or be turned by an obstetrician by the time you are in labor. Here are some abnormal delivery positions you should be aware of:
- Breech: The most common alternate delivery position is breech, in which the baby's bottom is down. In a complete breech position, he is butt-first with knees bent; in a frank breech, the legs are extended up, with feet near the head; if one leg is lowered over the cervix it is a footling breech. Approximately 3 in 100 babies approach their delivery date in a breech position.
- Occiput posterior: This position is similar to occiput anterior (the normal position, in which the baby is head-down), except that the baby faces the mother's front, instead of her back. These babies may rotate during labor to the easier-to-deliver occiput anterior position.
- Transverse: A baby in the transverse position is sideways, usually with his shoulders or back over the cervix. Sometimes referred to as a shoulder or oblique position.
Rare abnormal delivery positions include face-first, brow-first, and compound, in which a hand or foot emerges from the birth canal with the head or buttocks.
Symptoms And Diagnosis
Your health care provider will usually assess the position of the baby before you go into labor by feeling your uterus. A suspected abnormal position can be confirmed with ultrasound, and you and your health care provider can discuss the safest delivery options.
A few abnormal positions are more likely to occur under specific circumstances:
- Breech: You are more likely to have a breech baby if you go into labor prematurely or have an abnormally shaped uterus, fibroids, excessive amniotic fluid, more than one baby in the womb, or placenta previa. Placenta previa is a condition in which the placenta is positioned in the low portion of the uterine wall, partially or completely blocking the cervix.
- Transverse: The risk for having a baby in the transverse position increases if you go into labor prematurely, have given birth five or more times, or have placenta previa.
- Breech: If your baby is in a breech position after 36 weeks gestation, your doctor may attempt to guide the baby into the correct position by pushing gently on your belly while viewing fetal movement with ultrasound (external cephalic version). If the baby is still breech when labor begins, your doctor usually delivers the baby by cesarean section.
In some cases, a breech vaginal birth may be possible, especially in a pregnancy with multiple gestations (such as twins or triplets), although the American College of Obstetricians and Gynecologists (ACOG) recommends that breech babies be turned by external cephalic version or delivered by planned c-section. A large study found that breech babies delivered through the vagina had an increased risk of problems. This is, in part, because an infant who arrives feet- or butt-first can get his head stuck in the birth canal. The infant's body does not stretch the birth canal wide enough for the head to pass through, and the base of the baby's skull cannot compress or mold to the birth canal as it does during a headfirst passage. This can cause a prolonged labor and fetal distress. Discuss your particular situation with your doctor.
- Occiput posterior: In this position, vaginal delivery is possible but more difficult for you and the baby. Labor is often prolonged. Sometimes the doctor uses forceps to help out the baby. Your doctor may opt to deliver the baby by cesarean section, depending on the risks.
- Transverse: Your doctor will deliver the baby by cesarean section, either right when you start labor, or a little earlier. Unless the baby can be turned by external cephalic version into a head first position, a vaginal birth would be too risky for you and the baby.
With all abnormal positions, there is additional risk to the mother and fetus. A damaged or obstructed umbilical cord may threaten the baby's oxygen supply. If the baby goes without oxygen for too long, he can develop brain damage or even die. There is also an increased risk of cervical or vaginal tears with abnormal positions.
Frequently Asked Questions
Q: If I had a pregnancy with an abnormal position, what are the chances it will happen again?
A: If the baby was positioned abnormally because of the shape of your pelvis or your uterus, your chances of having an abnormal position in your next pregnancy are increased. In other cases, the position may have been associated with a condition, such as premature labor or placenta previa and would not happen in another pregnancy, unless that condition occurred again.
Zev Williams MD, PhD, FACOG, Reproductive Medicine and Infertility, Weill-Cornell Medical Center, New York, NY. Review provided by VeriMed Healthcare Network.
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