Understanding the process of labor and delivery should help you know what to expect. Although it’s impossible to predict exactly the way labor will progress, there are specific stages that mother and baby undergo as birth approaches. The mechanisms of labor describe the fetal position changes that occur as the baby moves down into the birth canal, states professor Neil K. Kochenour, with the University of Utah College of Medicine.
Learn the specific sequence of labor, also called the “cardinal movements.” The normal sequence includes engagement, descent, flexion, internal rotation, extension, restitution/external rotation and expulsion, according to Yvonne Cheng, M.D., et al. from a Medscape article entitled “Normal Labor and Delivery."
Realize that engagement occurs first and involves the baby’s head moving into the middle of the mother’s pelvis, according to physician Karen Kassel, with the Crouse Hospital website. Healthcare professionals describe the baby’s descent through the pelvis by “stations,” with “0 station” describing engagement.
Understand that the baby’s descent involves flexing of the baby’s head to ensure that it fits through the pelvis effectively. Flexion is a part of the sequence or mechanism of labor. As the baby’s head flexes and descends lower, it also rotates for the most effective fit.
Note that the extension, restitution and external rotation phases of labor involve the delivery of the baby’s head, according to physician Jose A. Lopez-Zeno, with the Ponce School of Medicine. After the baby’s head emerges, the expulsion stage will deliver the baby’s shoulders and body.