Amenorrhoea is the absence of at least 3 menstrual periods in the fertile age. This is not uncommon for young women and girls and during the transition.
If menstruation at the age of 16 (or later) has not yet occurred, this is called primary amenorrhoea. Often the cause is a late development, but there may be other factors, for example a disorder of the sexual organs or a mental illness.
Secondary amenorrhoea is the absence of menstruation in women who have previously had their cycle. Here too the causes can be physical (eg pregnancy), but also psychological (eg stress, depression or anorexia).
When amenorrhea occurs as a result of a hormone regulation disorder without an organic condition being observed, one speaks of functional amenorrhoea.