Final answer:
Less than 5 percent of singleton pregnancies result in a breech presentation, which is typically delivered via Caesarian section in modern obstetric practice.
Step-by-step explanation:
In fewer than 5 percent of singleton pregnancies, infants are found to be in a breech presentation, where the baby is oriented buttocks down or with feet down. This presentation includes two main types: complete breech, where both legs are crossed and pointed downward, and frank breech, where the legs are pointed upward towards the baby’s head. Historically, before the 1960s, vaginal delivery of a breech presentation was more common, but in current practice, a Caesarian section is often the method of delivery for such cases.
Changes in delivery practices over time indicate evolving approaches to ensure the safety and health of both the mother and the infant during childbirth. The majority of presentations at birth, however, are the vertex presentation known as occiput anterior vertex, which is associated with a greater ease of vaginal birth compared to the breech presentation.