The hormone progesterone triggers the smooth muscles of the uterine wall to begin the contractions of labor.

Question

Quizplus · Accepted Answer

Progesterone actually helps maintain the pregnancy by keeping the uterine muscles relaxed and not triggering labor. It is the decrease in progesterone levels along with an increase in other hormones like estrogen and prostaglandins that contribute to the initiation of labor contractions.

The Hormone Progesterone Triggers the Smooth Muscles of the Uterine