A pubescent girl spends about half her waking moments wondering if she's normal. Are her breasts ever going to grow (or ever stop growing)? Do other girls get hair on their stomachs/nipples/upper lips? And all those sexual desires -- do they make her a total weirdo?
For a lot of women, the frequent peer comparisons don't end in adolescence. But while many are perfectly at ease talking about bikini-line hair removal, periods are often shrouded in a little more secrecy. A woman may not hesitate to ask a stranger in the bathroom for a tampon, but she may feel uncomfortable asking a friend about how heavy her flow is. She may even find it difficult to talk to her gynecologist.
And when it's not being discussed, it's hard to know what exactly "normal" is.
The normal range for a woman's menstrual cycle is from 21 to 35 days, and the average period lasts from four to seven days [source: Cleveland Clinic]. An abnormal cycle is one that's shorter or longer than that range, or one that's infrequent or absent altogether. If a woman's period is extremely light or extremely heavy, or very painful, those are also indicators that something may be amiss.
The question of whether or not her menstrual cycles are normal becomes most important if and when she wants to conceive. The more regular they are, the better the opportunity to chart her ovulation accurately -- and determine the best time to have sex to get pregnant. And if her cycles are abnormal, there's a chance that a medical condition is to blame, one that will need to be treated before she can conceive.
So what can cause a woman's cycle to go awry?