Late breakthrough bleeding or amenorrhea may indicate that the oral contraceptive has:

• A. Not enough estrogen
• B. Too much estrogen
• C. Not enough progestin
• D. Too much progestin

Answer: (C)

Late breakthrough bleeding or amenorrhea in the context of oral contraceptive use typically points to insufficient progestin in the contraceptive formulation. Progestin plays a crucial role in stabilizing the endometrial lining and preventing uterine bleeding. When the progestin levels are inadequate, the endometrium may not be properly maintained, leading to unexpected bleeding patterns, including late breakthrough bleeding or even a complete cessation of menstrual bleeding (amenorrhea).

Hormonal contraceptives often contain a combination of estrogen and progestin, and it's the progestin component that is mainly responsible for counteracting the proliferative effects of estrogen on the uterine lining. If the progestin is insufficient, it can result in an unstable endometrial environment, resulting in the types of bleeding mentioned.

Other options mentioning estrogen do not correctly identify the cause of late breakthrough bleeding or amenorrhea as they are generally linked to the stability of the endometrium and secretion patterns induced by progestin.