Absence of menstrual periods for more than 3 months or a woman who has never had a period.
There are many causes of amenorrhea but you should first check whether you are pregnant by performing a home pregnancy test.
If your first period has not occurred after the age of 16, you should consult a physician.
If the pregnancy test is positive, you should make an appointment with a gynecologist before the 12th week of absence of menstrual periods, and sooner if you have pain in the lower abdomen and/or bleeding, even if minor.