How do you know if your period is regular or irregular? I can't
figure mine out! The fact that the word "cycle" is used to
describe a menstrual period makes it seem as though it happens
like clockwork every 4 weeks. But the truth is that there is a
lot of normal variation in cycle length. A girl's monthly cycle
— the number of days from the start of her period to the start
of the next one — is, on average, 28 days. But cycle lengths
vary — some girls have a 24-day cycle, some have a 34-day cycle.
And it's not unusual, especially in the first few years after
beginning menstruation, to skip periods or to have an irregular
menstrual cycle. Other things that affect cycles include diet,
stress, exercise, and, occasionally, illness. If your period
isn't coming regularly, is especially uncomfortable, or has
stopped (if you are sexually active this may be a sign of
pregnancy), you should see a health professional. Most of the
time, though, some variation is normal. Reviewed by: Larissa
Hirsch, MD Date reviewed: Augus