External cephalic version (ECV) is a procedure used during pregnancy to turn a baby from a breech position to a head-down position through gentle pressure applied to the mother’s abdomen. When a baby remains bottom-down or feet-down in the womb after 36 weeks of pregnancy, this procedure offers an alternative to cesarean delivery, potentially increasing the chances of a vaginal birth.

Epidemiology

Breech presentation is relatively common earlier in pregnancy but becomes less frequent as the due date approaches. At around 28 weeks of pregnancy, almost one-fourth of all babies are in a breech position. However, most babies naturally turn head-down as pregnancy progresses. By the time a pregnancy reaches full term, only about 3 to 4 out of every 100 babies remain in a breech position.^[1][2]

Around 36 weeks of pregnancy, most babies will naturally move into a head-down position, which is ideal for vaginal delivery. When this doesn’t happen, the breech presentation becomes a concern for delivery. If a baby is still breech at 36 weeks, it is unlikely to turn on its own into a head-down position.^[3][5]

Breech presentation has become the third most common reason for cesarean delivery worldwide, accounting for nearly 17 percent of all cesarean sections. The global cesarean section rate has increased from approximately 23 percent to 34 percent in the past decade, and fetal malpresentation plays a significant role in this trend.^[2]

In current clinical practice, most pregnancies with a breech baby are delivered by cesarean section. Approximately 12 percent of cesarean deliveries in the United States are performed specifically because of breech presentation, ranking it as the third most frequent indication for surgical delivery after previous cesarean section and labor complications.^[4]

Causes

In most cases, there is no clear explanation for why a baby remains in a breech position. The majority of breech presentations occur without any identifiable cause, and the babies themselves are typically normal and healthy.^[3]

However, several factors may contribute to a baby staying in a breech position. Multiple pregnancies, such as twins or triplets, can limit the space available for each baby to turn. The amount of amniotic fluid—the liquid that surrounds and cushions the baby in the womb—can also play a role. Having too much or too little amniotic fluid may affect the baby’s ability to move into the correct position.^[3]

The shape and condition of the uterus can influence fetal positioning. Women with an abnormally shaped uterus or those with growths such as fibroids (noncancerous tumors in the uterus) may be more likely to have a breech baby. Placenta previa, a condition where the placenta covers all or part of the opening of the uterus, is another factor that can prevent a baby from turning head-down.^[3]

Prematurity is associated with breech presentation because babies born early may not have had enough time to naturally settle into the head-down position. Additionally, poor uterine tone, which means the muscles of the uterus are not as firm as they should be, may make it easier for a baby to remain in various positions rather than settling head-down.^[4]

Risk Factors

Certain circumstances make it more likely that a baby will remain in a breech position as the pregnancy approaches term. Women who have been pregnant before may experience breech presentation, though the relationship between parity and breech is complex—while previous pregnancies can affect uterine tone, they also relate to success rates when attempting to turn a breech baby.^[3]

First-time mothers appear to face different challenges. When external cephalic version is attempted, nulliparity—meaning this is the woman’s first pregnancy—is associated with lower success rates in turning the baby. This may be because the uterine muscles and abdominal wall are tighter in women who have never given birth before.^[13]

Having more than one baby in the uterus, such as twins or triplets, increases the likelihood of at least one baby being breech. The limited space and the positioning of multiple babies make it physically more difficult for all babies to be head-down at the same time.^[1]

Structural differences in the reproductive system can create an environment where breech presentation is more common. Women with uterine anomalies—meaning their uterus has an unusual shape or structure—or those with large fibroids may find their babies are more likely to settle in a breech position. Breech is more common when the womb has a different shape than usual.^[1][5]

Symptoms

Breech presentation itself does not cause symptoms that a pregnant woman can feel. Most women cannot tell by sensation alone whether their baby is head-down or breech. The position of the baby is typically discovered during routine prenatal checkups when a healthcare provider examines the abdomen or performs an ultrasound.^[3]

Healthcare professionals can often determine the baby’s position by placing their hands on the mother’s abdomen and feeling where the baby’s head, back, and buttocks are located. This physical examination helps identify which part of the baby is presenting first—meaning which part would come out first during delivery. An ultrasound exam or pelvic exam may be used to confirm the breech position if there is any uncertainty.^[3]

There are three main types of breech presentation, each describing how the baby is positioned. In a frank breech, which is the most common type, the baby is bottom-first with the thighs against the chest and feet up by the ears. In a complete breech or flexed breech, the baby is bottom-first with the thighs against the chest and the knees bent. A footling breech, sometimes called incomplete breech, occurs when one or both of the baby’s feet are below the bottom, positioned to come out first.^[2][5]

While a breech position doesn’t cause symptoms for the mother, it does create concerns for delivery. Breech pregnancies are not dangerous during pregnancy itself, but complications can arise when it’s time for the baby to be born. A vaginal breech delivery is more challenging than a head-down birth and carries certain risks for both the baby and the mother.^[1]

Prevention

There is no guaranteed way to prevent a baby from being in a breech position, as most cases occur without a known cause. However, understanding when and how to address breech presentation can help avoid the need for cesarean delivery in many cases. External cephalic version offers an opportunity to turn a breech baby before labor begins, potentially preventing the complications associated with breech birth.^[1]

The timing of intervention is important for prevention strategies. Healthcare providers typically begin assessing fetal presentation starting at 36 weeks of pregnancy. Waiting until 37 weeks before attempting external cephalic version is preferable because this timing offers several advantages. By 37 weeks, if the baby is going to turn spontaneously, it is likely to have already done so. The risk of the baby turning back to breech after a successful version is also decreased at this gestational age.^[13]

Attending regular prenatal appointments helps ensure that breech presentation is identified early enough to consider options like external cephalic version. Between 20 to 30 percent of eligible women are not offered this procedure, which means missed opportunities to prevent cesarean deliveries that are performed solely because of breech presentation.^[13]

Some women may explore alternative approaches to encourage their baby to turn, though these methods vary in their evidence and effectiveness. While various techniques have been suggested in different cultures and medical traditions, the most evidence-based approach to preventing a breech birth remains external cephalic version performed by a trained healthcare provider.^[1]

Pathophysiology

Understanding how external cephalic version works requires knowledge of the normal changes that occur in the uterus and the baby’s position as pregnancy progresses. During the early and middle stages of pregnancy, babies have plenty of room to move around in the amniotic fluid. They frequently change position, and breech presentation is very common during these weeks. This freedom of movement is why breech is found in about one-fourth of pregnancies at 28 weeks.^[2]

As pregnancy advances toward term, the baby grows larger and the relative amount of space inside the uterus decreases. The baby’s head is typically the heaviest part of the body, and gravity, along with the shape of the mother’s pelvis and uterus, usually encourages the head to settle downward. By 36 to 37 weeks, most babies have naturally moved into a vertex or head-down presentation, which is the ideal position for vaginal delivery. The head fits well into the rounded lower portion of the uterus and the pelvis, making this the most stable and common position.^[1]

When a baby remains breech, the mechanics of delivery become more complex. In a breech presentation, the buttocks or feet would be born first, followed by the body, with the head coming last. Because the head is the largest part of the baby, delivering it last can lead to complications. The cervix may not be fully dilated enough for the head to pass through easily, or the umbilical cord could become compressed, reducing oxygen supply to the baby. These mechanical challenges are why breech presentations are associated with higher risks during vaginal delivery.^[4]

External cephalic version addresses this problem by manually changing the baby’s position while still in the uterus. The procedure works by applying firm, controlled pressure to the mother’s abdomen. The healthcare provider uses their hands on the outside of the belly to guide the baby through a rotation, either by a forward roll or a backward flip maneuver. The goal is to move the baby’s head from the top of the uterus down into the pelvis, positioning it to be born first.^[4]

The success of external cephalic version depends on several physical factors. The amount of amniotic fluid plays a crucial role—adequate fluid allows the baby to move more easily during the turning process. The tone of the uterine muscles is also important. A relaxed uterus makes it easier to manipulate the baby’s position, which is why medications called tocolytics are often given before the procedure. These medications temporarily relax the uterine muscles, creating better conditions for the version attempt.^[5]

The most commonly used tocolytic for external cephalic version is terbutaline or salbutamol, which belongs to a class of drugs called beta-stimulants. When injected under the skin, these medications cause the uterine muscles to relax within minutes. Women may notice their heart beating faster after receiving this medication, which is a normal response that typically stops after a few minutes. The medication has been shown to double the success rate of external cephalic version attempts.^[5][13]

During the procedure, ultrasound monitoring provides continuous visualization of the baby’s position and the location of the umbilical cord. The baby’s heart rate is carefully monitored before, during, and after the procedure to ensure that the baby is not experiencing distress. If the baby’s heart rate shows concerning changes or if the mother experiences significant pain, the procedure is stopped immediately.^[1]

The physical process of turning can cause temporary cramping and discomfort for the mother as pressure is applied to the abdomen. The pressure lasts several minutes during each attempt to rotate the baby. Many healthcare providers offer pain medication, though this is optional. The discomfort is usually brief and resolves once the procedure is completed.^[1]

Not all breech babies can be turned successfully with external cephalic version. The average success rate is approximately 58 to 60 percent, meaning a little more than half of all attempts result in the baby being turned to a head-down position. Some babies who are successfully turned may rotate back to breech before labor begins, though this is less common when the procedure is performed at 37 weeks or later.^[1][2]

Several factors influence whether external cephalic version will be successful. Women who have had previous pregnancies tend to have higher success rates, likely because their abdominal and uterine muscles are more relaxed. Babies in a transverse or oblique lie—meaning positioned sideways across the uterus rather than vertical—may actually be easier to turn than those in a straight breech position. Factors associated with lower success rates include being pregnant for the first time, advanced cervical dilation, estimated fetal weight less than 2,500 grams, having the placenta located on the front wall of the uterus, and the baby’s head being engaged low in the pelvis.^[13]

When external cephalic version is successful and the baby remains in a head-down position until labor begins, the woman has significantly improved chances of having a vaginal delivery. This reduces the need for cesarean section, which is major abdominal surgery with its own set of risks and longer recovery time. By addressing the mechanical problem of breech presentation before labor starts, external cephalic version can transform the planned mode of delivery and potentially improve outcomes for both mother and baby.^[1]