The McRoberts maneuver is a repositioning technique used during vaginal delivery when a baby’s shoulder gets stuck behind the mother’s pubic bone, a complication called shoulder dystocia. It involves flexing the mother’s legs sharply toward her abdomen, which changes the angle of her pelvis and gives the baby more room to pass through. It is the first technique most delivery teams reach for when shoulder dystocia occurs, and it resolves the problem about 42% of the time on its own. That number climbs to roughly 95% when combined with other hands-on techniques.
Why Shoulder Dystocia Requires Immediate Action
Shoulder dystocia happens when a baby’s head delivers but the front shoulder catches on the mother’s pubic bone. The baby’s body stays inside the birth canal, and the umbilical cord can become compressed between the baby and the pelvic wall. This cuts off the baby’s oxygen supply, so the delivery team has only minutes to free the shoulder and complete the birth.
The situation is unpredictable. While larger babies, gestational diabetes, and prolonged labor raise the risk, shoulder dystocia also occurs in deliveries with no obvious risk factors. Delivery teams train for it specifically because speed and technique matter more than anything else once it’s recognized.
How the Maneuver Works
During the McRoberts maneuver, two assistants each take one of the mother’s legs and flex them sharply back toward her shoulders, bringing the knees as close to the chest as possible. The mother lies flat on her back for this. The sharp hip flexion doesn’t physically push the baby out. Instead, it changes the geometry of the pelvis in ways that free the trapped shoulder.
X-ray studies have measured exactly what happens inside the pelvis during this leg repositioning. The pubic bone rotates upward (toward the head), and the sacrum, the triangular bone at the base of the spine, flattens out. The angle between the pubic bone and the top of the sacrum increases from about 38 degrees to nearly 52 degrees. At the same time, the tilt of the pubic bone relative to horizontal drops by 24%. The angle at the base of the lumbar spine also opens up, going from about 134 degrees to 140 degrees.
In practical terms, the front wall of the pelvis lifts away from the baby’s shoulder while the back wall straightens, creating a wider, straighter path. The baby doesn’t move. The pelvis moves around the baby.
What It Looks Like in the Delivery Room
If you’re the person giving birth, here’s what to expect. The moment the delivery team recognizes shoulder dystocia, things move quickly. You’ll be asked to lie flat, and two people will take your legs, bending them up and back toward your chest. It can feel like an intense stretch, especially if you don’t have an epidural. The team will likely time the maneuver with a contraction, when your body is already pushing the baby downward.
In many cases, the delivery team will also apply suprapubic pressure at the same time. This means someone places the heel of their hand just above your pubic bone and pushes downward and to the side, nudging the baby’s shoulder out from behind the bone. The McRoberts maneuver alone works about 42% of the time, but combining it with suprapubic pressure or delivering the baby’s back arm first raises the success rate to around 95%.
The entire sequence often takes less than a minute or two. If it doesn’t work, the team moves to additional techniques, but the McRoberts maneuver is nearly always the starting point because it’s fast, non-invasive, and effective more often than not.
When the Maneuver Is Difficult to Perform
A few situations can make the sharp hip flexion hard or impossible. Obesity can make it physically challenging to bring the legs far enough back. A dense epidural that blocks motor control in the legs means the mother can’t assist with positioning, and the assistants have to manage the full weight of both legs. Mothers with pelvic fractures, spinal cord injuries, severe arthritis, or neuromuscular disorders may not be able to tolerate the position or achieve the range of motion it requires. In these cases, the delivery team may need to skip directly to other shoulder dystocia techniques.
Risks for Mother and Baby
The maneuver itself is considered low-risk compared to shoulder dystocia complications, but it’s not risk-free. For the mother, the extreme hip flexion can cause temporary nerve irritation along the outer thigh, a result of stretching the nerve that runs near the hip crease. Tearing of the perineum is common during any shoulder dystocia delivery, and in rare cases the pubic joint itself can separate slightly from the force involved. Postpartum bleeding is also more likely after a complicated delivery.
For the baby, the main concern during any shoulder dystocia is injury to the bundle of nerves that runs from the neck into the arm. If the shoulder is wedged tightly and pulled during delivery, these nerves can stretch or tear, potentially causing weakness or loss of movement in the affected arm. Bone fractures, typically of the collarbone, can also occur. These risks are tied more to the shoulder dystocia itself than to the McRoberts maneuver specifically, which is designed to minimize the force needed to complete the delivery.
Why It’s the First-Line Response
The McRoberts maneuver became widely adopted after it was described in obstetric literature in 1983 by a team at the University of Texas. It’s named after William Alexander McRoberts, the obstetrician who championed the technique. Its appeal is straightforward: it requires no instruments, no surgical incisions, and no internal manipulation of the baby. It changes the pelvic angles enough to resolve many cases of shoulder dystocia with positioning alone. When it doesn’t work by itself, it still improves the pelvic geometry for whatever technique comes next, making it a useful foundation rather than a wasted step.