Estrogen rise in late pregnancy promotes production of what substances to prepare for labor?

• A. Insulin
• B. Adrenaline
• C. Cortisol
• D. Prostaglandins

Answer: (D)

As pregnancy nears term, rising estrogen stimulates the production of prostaglandins in the decidua and fetal membranes. Prostaglandins, especially PGE2 and PGF2alpha, are key players in preparing for labor: they soften and ripen the cervix and ramp up uterine contractility. Estrogen also increases the uterus’s responsiveness by upregulating oxytocin receptors and promoting gap junction formation in the myometrium, making contractions more coordinated and effective.

Insulin, adrenaline, and cortisol aren’t the primary substances promoted by estrogen to ready the body for labor. The prostaglandins are the main mediators linking the late-pregnancy estrogen rise to the onset of labor.