A vaginal delivery is the birth of offspring (babies in humans) in mammals through the vagina. It is the natural method of birth for all mammals except monotremes, which lay eggs into the external environment. The average length of a hospital stay for a normal vaginal delivery is 36–48 hours or with an episiotomy (a surgical cut to widen the vaginal canal) 48–60 hours, whereas a C-section is 72–108 hours. Different types of vaginal deliveries have different terms:
An assisted vaginal delivery (AVD) occurs when a pregnant female goes into labor (with or without the use of drugs or techniques to induce labor), and requires the use of special instruments such as forceps or a vacuum extractor to deliver her baby vaginally.
An instrumental vaginal delivery (IVD) is another term for an assisted vaginal delivery.
An induced vaginal delivery (also IVD) is a term for a delivery involving labor induction, where drugs or manual techniques are used to initiate the process of labor. Use of the term "IVD" in this context is less common than for instrumental vaginal delivery.
A normal vaginal delivery (NVD) is a term for a vaginal delivery, whether or not assisted or induced, usually used in statistics or studies to contrast with a delivery by cesarean section.
Note: Use of the term IVD is best avoided because of its duplicate meanings.