Toward the end of pregnancy, the fetus usually moves into a position where its head is near the birth canal. In a small percentage of cases, however, the fetus's head is at the top of the uterus and the buttocks are positioned near the birth canal, in what is called a breech presentation. Prior to delivery, manually shifting the fetus into proper position may be attempted. If the attempt is unsuccessful, a Cesarean section may be necessary.
Causes of Breech Presentation
A breech presentation does not always have a specific cause but, in some cases, results from the following:
- Abnormally shaped uterus
- Too much/too little amniotic fluid
- Multiple births
- Placenta previa
- Uterine fibroids
Breech presentation is also more common in women who have had several pregnancies, and in babies that are born prematurely.
Types of Breech Presentation
There are several types of breech presentation.
A complete breech occurs when the buttocks are near the birth canal, the knees are bent, and the feet are close to the buttocks.
In an incomplete breech, the buttocks and one foot are near the birth canal, and one foot is up near the head.
A frank breech occurs when the fetus's legs are stretched up and the feet are by the head, and the buttocks are close to the birth canal.
A footling breech occurs when one or both legs are stretched out below the buttocks, and are positioned to come out first. This type of breech is more common in preterm babies.
Diagnosis of Breech Presentation
To diagnose a breech presentation, the abdomen is felt by hand to determine the position of the fetus's head, back and buttocks. An ultrasound is usually then performed to confirm the fetus's position.
Recommendations for Breech Presentation
As labor gets closer, an external cephalic version (ECV) may be recommended. During an ECV, which is performed in conjunction with a fetal sonogram, a physician gently pushes on the mother's abdomen in an attempt to shift the fetus's position. The fetus's heart is monitored and, if the fetus goes into distress, an emergency C-section may be performed. Even if the doctor is successful in shifting the fetus, it is possible that it will change position again.
If an ECV is unsuccessful or if the mother decides against it, a Cesarean delivery may be recommended because of the risk of complications from a vaginal delivery. A vaginal breech birth can injure the fetus or mother, and there is a chance of umbilical-cord prolapse, in which the umbilical cord passes through the cervix before the fetus. If it does, it may be compressed or pinched, which can stop blood flow to the fetus.