What is the most common cause of secondary amenorrhea?

The most common cause of secondary amenorrhea is indeed pregnancy. Secondary amenorrhea is defined as the cessation of menstruation for three cycles or more in a woman who has previously menstruated regularly. Since pregnancy halts the normal menstrual cycle, it is a primary consideration when evaluating a woman with secondary amenorrhea.

In clinical practice, when a patient presents with secondary amenorrhea, the first step is to rule out pregnancy through a reliable pregnancy test. If pregnancy is confirmed, amenorrhea is naturally explained by the physiological changes that occur during gestation.

Assessing for other causes of secondary amenorrhea, such as ovarian failure, hypothalamic conditions, or anatomical abnormalities, is important but typically occurs only after pregnancy has been excluded. Thus, recognizing pregnancy as the most common cause is crucial for accurate diagnosis and appropriate management of the patient.