Typically, a fetus is born with a head-first presentation. A breech birth, or breech presentation, occurs when a fetus descends through the birth canal with the feet or buttocks first. Breech births are fairly common. They occur in roughly 1 out of 25 full-term births. Breech birth can cause serious complications or death if the fetus is not monitored carefully.
Types of Breech Birth
A frank breech is a type of breech birth during which the fetus’s buttocks are presented first. In frank breech, the fetal legs flex at the hip with extended knees. This causes the fetal feet to be positioned near the ears. Roughly 65% to 70% of breech birth cases take the frank breech position.
A complete breech position is less common than frank breech position. It occurs when the fetus’s hips and knees both flex. This results in the fetus sitting with crossed legs. The fetal feet are beside the bottom.
During a footling breech birth, one or both of the fetus’s feet are positioned first in the birth canal. This displaces the buttocks to a higher position in the womb. Footling breech births are rare at full term. However, this type of breech birth can be common with a premature birth.
A kneeling breech occurs when the fetus is presented in a kneeling position. One or both of the fetal legs lay extended at the hips. The legs are flexed at the knees. A kneeling breech is an extremely rare form of breech birth.
Risk Factors for Breech Birth
Prematurity is a main cause of breech birth. At 28 weeks gestation, 25% of fetuses are positioned for breech birth. At full term, roughly 3% of fetuses remain in breech birth position. Another main cause of breech birth is the shape of the mother’s uterus. Abnormalities in the uterus shape can be a reliable indicator of the final fetal position.
Other factors that can contribute to development of breech birth include:
- Prior cesarean section
- Contracted pelvis
- Congenital uterus malformation
- Abnormal amniotic fluid volume
- Multiple pregnancy, or more than one fetus in the same term
- Fetal anomalies such as anencephaly or hydrocephaly
- Placenta praevia, or the fetus growing in the lower womb and covering the cervix
Complications of Breech Birth
Breech birth can be hazardous to the mother and fetus. In many cases, the fetus can be turned in the uterus to restore proper head-first position. The fetus can also be delivered through cesarean section to reduce the risk of potentially fatal complications. In some cases, the medical practitioner chooses not to perform a cesarean section due to potential complications or risk factors. If a vaginal breech birth is performed, the mother and fetus should be monitored carefully to ensure that complications do not arise and that the fetus is not in distress.
Umbilical Cord Prolapse
Umbilical cord prolapse is a life-threatening complication that can occur. It is considered a medical emergency. During umbilical cord prolapse, the umbilical cord precedes the fetus. This often compresses the umbilical cord, resulting in a lack of oxygen and blood flow to the fetus. If the fetus is not delivered immediately, brain damage or death can result.
Head entrapment is more common during a preterm breech birth than a full-term breech birth. A full-term fetus typically has similarly sized hips and head. This allows the fetal hips and buttocks to dilate the mother’s cervix appropriately for a breech birth. When the fetus is premature, the head is typically larger than the buttocks. This can result in the head becoming entrapped due to inadequate dilation from the smaller buttocks.