A period is usually considered late when it does not come around the expected time in a person’s usual cycle. In most adults, cycles tend to last about 21 to 35 days, so a period that comes after that range may be considered delayed. A small change of a few days can still be normal, especially if cycles do not arrive on the exact same day every month.
A longer delay may need more attention. In adults, cycles that go beyond 35 days are outside the usual range, and in adolescents, cycles can be longer and may still be normal up to about 45 days. If someone who usually has regular periods goes 3 months without one, this is generally considered amenorrhea and should be checked by a doctor.
If you are experiencing a late period and believe pregnancy may be possible, taking a pregnancy test may be an important first step. Ongoing missed periods, repeated irregular cycles, or long gaps between periods should be evaluated by a gynecologist. It is important not to self-medicate or try to force a period to come without medical advice, because the cause may need proper treatment.