Prostaglandins are lipid mediators derived from arachidonic acid that play central roles in reproductive physiology, and in obstetrics two prostaglandin products are used to prepare the cervix and initiate labor. Dinoprostone is a prostaglandin E2 product available as the Cervidil vaginal insert, the Prepidil intracervical gel, and the Prostin E2 suppository used in the second trimester. Misoprostol is a prostaglandin E1 analog, marketed as Cytotec, used orally or vaginally for cervical ripening, labor induction, and postpartum hemorrhage. Before labor, the cervix undergoes a process called ripening in which it softens, effaces, and begins to dilate. When the cervix is unfavorable, reflected in a low Bishop score, prostaglandins accelerate this process so that induction is more likely to succeed. The Bishop score is a cervical assessment tool ranging from 0 to 13, and scores below 6 indicate an unfavorable cervix likely to benefit from a ripening agent. For the nurse, the central safety concerns are uterine tachysystole and the resulting fetal compromise, along with strict attention to contraindications, most importantly a prior uterine scar when misoprostol is being considered. A major...