Which of the following is a common intervention used in childbirth?

Induction is a common intervention used during childbirth to stimulate labor, either through medical means or natural methods. It is typically recommended when there are concerns for the health of the mother or baby, or when the pregnancy has gone past the due date. Medications such as oxytocin, or mechanical methods like breaking the waters, are often used in this process. Induction can help ensure that the labor occurs in a timely manner, reducing the risks associated with prolonged pregnancies.

In contrast, drug testing is generally part of prenatal care or hospital protocol, but it is not a common intervention in the actual childbirth process. Therapeutic abortion refers to the termination of pregnancy, which is a separate medical procedure not typically associated with childbirth itself. Routine ultrasound is a diagnostic tool used during pregnancy for monitoring fetal development and is not classified as an intervention during labor and delivery. Thus, induction stands out as the relevant intervention in the context of childbirth.