Amenorrhea as a term
Amenorrhea refers to the absence of menstruation, either as a result of lack of menarche (i.e. lack of menstruation by age 16) or absence of menstruation for more than 3 months in women who had previously experienced menstruation and who are not pregnant. Amenorrhea may be classed as physiological, or primary when it occurs during pregnancy, early lactation, or after menopause. Pathological, or secondary, amenorrhea is caused by several conditions.