Secondary amenorrhea is defined as

A woman who previously menstruated can develop secondary amenorrhea.Which is defined as absence of menstruation for three normal menstrual cycles. A woman with regular cycles and a delay of menses of even a week may warrant assessment with a pregnancy test.It is reasonable to evaluate a woman who has fewer than nine cycles per year.Reference: Berek and Novak's gynecology; 14th edition; Chapter 30; Amenorrhea