What is the most common cause of secondary amenorrhea?

The most common cause of secondary amenorrhea is pregnancy. Secondary amenorrhea refers to the absence of menstruation for three cycles or more in a woman who has previously had regular menstrual periods. Pregnancy is the most straightforward explanation for missed periods and should always be the first option considered when a woman presents with signs of amenorrhea.

Given the prevalence of unintended pregnancies, especially in populations where access to contraception may vary, it makes sense that pregnancy would represent the primary underlying cause of secondary amenorrhea. Other potential causes, such as hypothalamic dysfunction, ovarian failure, and uterine disorders, certainly play important roles in the differential diagnosis but are less common than pregnancy as a first consideration.