What is the most common cause of secondary amenorrhea in women?

The most common cause of secondary amenorrhea in women is indeed pregnancy. Secondary amenorrhea is defined as the absence of menstruation for three cycles or more in a woman who has previously had regular menstrual cycles. In the reproductive age group, pregnancy is the foremost reason for missed periods since it leads to hormonal changes that prevent ovulation and menstruation.

When considering secondary amenorrhea, it is essential to first rule out pregnancy through appropriate testing, as the likelihood of a pregnancy affecting the menstrual cycle is significantly high compared to many other causes. This makes pregnancy a predominant factor to consider in the diagnosis and understanding of menstrual irregularities.

Other factors, like ovarian failure or conditions like hypothalamic amenorrhea, can certainly contribute to secondary amenorrhea; however, they are less common than pregnancy. Conditions such as an imperforate hymen usually present at a younger age and do not typically account for secondary amenorrhea in women who have previously had regular menstrual cycles.