Which synthetic hormone can be administered to stimulate labor in pregnancy?

• A. Progesterone
• B. ADH
• C. Oxytocin
• D. Estradiol

Answer: (C)

The main idea here is how labor is induced pharmacologically. Oxytocin is the hormone that directly stimulates uterine contractions by acting on receptors in the uterine smooth muscle, increasing calcium signaling and driving stronger, more frequent contractions. A synthetic form of oxytocin can be given by IV with careful dosing to start labor or to augment a labor that’s progressing slowly, and it may also aid in promoting milk let-down after birth.

Progesterone, on the other hand, helps maintain pregnancy by keeping the uterus less contractile, so it would not promote labor. ADH (vasopressin) mainly regulates water balance and blood pressure and has no role in initiating uterine contractions. Estradiol influences uterine growth and responsiveness and is involved in preparing the uterus, but it is not used as a direct agent to induce labor; clinical induction relies on oxytocin (and sometimes prostaglandins for cervical ripening) rather than estrogen therapy.