Amenorrhoea :
Amenorrhoea is the absence of periods either due to hormonal changes or certain reproductive disorders. Primary amennorhoea is said to take place when a teenage girl does not have her normal menstrual cycle even past the age of 15 years. On the other hand, secondary amenorrhoea is said to occur when a woman who is experiencing normal periods, suddenly does not have it for 3 or more months successively.
Both these types have different underlying causes. If amenorrhea is not treated on time, it can increase the risk of developing cardiovascular disease, early-onset oseteoporosis, etc.