Everyone's periods are on a little different of a schedule, especially if you aren't on birth control, but Dr. Nachtigall defined an irregular period as one that is more frequent than every 21 days or less frequent than every 42 days.
"People who have fewer than nine periods a year, that's something that should be evaluated, and some people with PCOS don't have any periods at all," she explained. "They have complete absence [of a period], called amenorrhea." Irregular periods are due to a hormonal balance; people with PCOS have more androgen and don't ovulate.
Irregular periods is one of the biggest indicators of PCOS. If you're not trying to get pregnant and you don't object to taking oral contraceptives, Dr. Nachtigall said you can get your periods back on schedule by taking a birth-control pill combining estrogen and progesterone.
