Final answer:
During childbirth, the most common orientation is Head first, head down, which is known as the vertex presentation. Breech presentations occur in fewer than 5 percent of births and often lead to a Caesarian section.
Step-by-step explanation:
Orientation of the Baby During Childbirth
During childbirth, the most common and expected orientation of a baby coming from the birth canal is Head first, head down. This is known as the vertex or occiput anterior presentation, where the smallest part of the baby's head (the occiput) exits the birth canal first. The baby's face is oriented towards the maternal spinal cord during this process. In the expulsion stage of labor, which is the second stage, the baby's head enters the birth canal and is then followed by the rest of the body leading to birth.
In contrast, in fewer than 5 percent of births, the baby can be in a breech presentation, which is when the buttocks are oriented down. This can be further specified as a complete breech, where both legs are crossed and facing downward, or a frank breech, with the legs oriented upward. Nowadays, breech births are more commonly delivered through Caesarian section.