Final answer:
After the baby's head is delivered, it is usually tilted to facilitate the birth of the rest of the body. The expulsion stage can last up to 2 hours, and most babies are born in the occiput anterior vertex position. Breech presentations, occurring in fewer than 5% of births, are now commonly delivered via Cesarean section.
Step-by-step explanation:
After the baby's head is delivered, it is usually tilted to facilitate the delivery of the shoulders and the rest of the body. This process is a critical part of the expulsion stage of childbirth. When the fetal head enters the birth canal, the typical duration of this stage can range up to 2 hours, with considerable variation based on the fetus's orientation. The most common and easiest orientation for vaginal birth is the occiput anterior vertex position, where the fetus's head is facing the maternal spinal cord, allowing the smallest part of the head to exit first.
In the case of breech presentations, which occur in fewer than 5 percent of births, the orientation of the infant is buttocks down. There are different types of breech presentations, including the complete breech and the frank breech. A complete breech has both legs crossed and oriented downward, while in a frank breech, the legs are oriented upward. Historically, breech births were more frequently delivered vaginally, but modern practices favor Cesarean sections for these scenarios.
Immediately following the delivery of the head, an obstetrician typically aspirates mucus from the newborn's mouth and nose before the newborn takes its first breath. The rest of the baby's body usually follows the head quickly. The umbilical cord is then double-clamped and cut, severing the newborn's physical connection to the placenta and officially marking the conclusion of the second stage of childbirth.