Which hormones are produced by the ovaries during the menstrual cycle? Select all that apply.

Menstruation marks the beginning of the menstrual cycle and involves the shedding of the functional layer of the endometrium due to the decline of progesterone and estrogen. It is triggered by corpus luteum regression in the absence of fertilization. Normal menstrual bleeding lasts 3–7 days, with average blood loss between 30–80 mL. Levels of FSH (3–20 IU/L) begin to rise to recruit new follicles for the next cycle. Prostaglandins are released, causing vasoconstriction and myometrial contractions, leading to menstrual cramps and tissue expulsion.

Rationale for correct answer

B. The normal duration of menstruation is 3–7 days. This range is physiologically typical and supported by stable hormone withdrawal patterns and normal endometrial responses.

Rationale for incorrect answers

A. A duration of 1–3 days is shorter than the normal range and may indicate hypomenorrhea or hormonal insufficiency, though still considered normal if consistent and asymptomatic.

C. Bleeding for 7–10 days exceeds the upper normal limit and may suggest menorrhagia or coagulation abnormalities, requiring evaluation.

D. A menstrual duration of 10–14 days is abnormal and often pathological. It may suggest hormonal imbalance, fibroids, endometrial hyperplasia, or bleeding disorders.

Take home points

• Normal menstruation lasts 3–7 days with 30–80 mL blood loss.
• Bleeding <3 days or >7 days may indicate hormonal or structural pathology.
• Menstruation occurs due to hormonal withdrawal after corpus luteum regression.
• Prostaglandins play a role in endometrial shedding and cramping.

hCG is a glycoprotein hormone secreted by the trophoblast cells of the developing embryo shortly after implantation, typically detectable in maternal serum by day 8–10 post-ovulation. Its primary role is to rescue the corpus luteum, preventing its degeneration and allowing continued secretion of progesterone and estrogen. These hormones maintain the decidualized endometrium, preventing menstruation and supporting early pregnancy. hCG shares structural similarity with LH and binds to LH receptors on the corpus luteum. Peak serum hCG levels reach 100,000–200,000 mIU/mL by 10 weeks gestation.

Rationale for correct answer

C. hCG prevents luteolysis by acting on LH receptors of the corpus luteum, maintaining its progesterone production. This sustains the endometrial lining for implantation and early embryonic development.

Rationale for incorrect answers

A. hCG does not stimulate new follicle development. In fact, high progesterone and estrogen levels maintained by the corpus luteum inhibit FSH, preventing new folliculogenesis during early pregnancy.

B. hCG prevents menstruation by maintaining the corpus luteum and its hormone output. Menstruation is triggered by progesterone withdrawal, which hCG directly prevents.

D. hCG supports the continued production of progesterone, not its inhibition. It ensures the endometrial lining remains intact until the placenta takes over hormone production around week 10–12.

Take home points

• hCG maintains the corpus luteum during early pregnancy.
• It prevents menstruation by supporting progesterone production.
• hCG mimics LH and binds to LH receptors on luteal cells.
• It does not promote follicle development or suppress progesterone.