During a vaginal birth, if the baby's head emerges and then retracts back against the perineum, what should the nurse prepare for?

When the baby's head emerges and then retracts against the perineum, this indicates that the baby may be experiencing shoulder dystocia. In this situation, the McRoberts maneuver is the most appropriate preparation. This technique involves the mother bringing her knees to her chest, which alters the pelvic shape and can help to resolve the dystocia by providing more room for the baby's shoulders to maneuver past the pubic symphysis.

The McRoberts maneuver is often one of the first interventions employed in cases of shoulder dystocia because it is simple to execute and can produce quick results. It effectively reduces the angle of the pelvis, ultimately facilitating the delivery of the baby. By preparing for this maneuver, the nurse is taking a proactive approach to managing a critical situation that could impact the health of both the mother and the baby.

In contrast, while suprapubic pressure and the Woods screw maneuver are also techniques used in managing shoulder dystocia, the McRoberts maneuver is usually prioritized as a first-line intervention. Lowering the head of the bed may not specifically address the immediate need to relieve the shoulder obstruction.