Question

Some birth control pills contain synthetic estrogen and progesterone; which of the below options describes their mechanism of action?

• A. Increased natural production of progesterone from corpus luteum
• B. They keep a check on the secretion of FSH and LH from the pituitary, thus preventing ovulation
• C. They cause sloughing off of the uterus lining
• D. They trigger premature ovulation

Answer 1

The correct option is B They keep a check on the secretion of FSH and LH from the pituitary, thus preventing ovulation

Hormonal or steroidal birth control pills consist of either synthetic progesterone alone or estrogen - progesterone combination which affects the process of ovulation.

The main mechanism of action are the inhibition of follicular development, ovulation, and as consequence, corpus luteum formation. Further, it is also involved in the alteration of the cervical mucus that inhibits sperm penetration.The progesterone in the pills causes inhibition of GnRH secretion from hypothalamus, which in turn reduces the LH and FSH secretion from anterior pituitary. Without FSH, follicles do not mature in the ovary and subsequently ovulation does not occur.

Sloughing off of the uterine lining occurs naturally during the menstrual phase.

The hormonal pills do not trigger premature ovulation, neither do they increase progesterone production from corpus luteum.