I have yet to meet a women who doesn't complain about her period. Goodness knows I have. We worry about it's arrival each month (admit it -- you've counted days on a calendar worrying about whether "it" will come during prom or your wedding or your beach vacation). But when it doesn't arrive like clockwork, that's worrisome in a whole other way. For women with irregular periods the question is usually "why?"

Researchers from four universities surveyed women and found that only 28% had perfectly regular cycles. The reasons for irregular periods vary. Here are just some of the possibilities:

• Late periods. If you're over 45 and your periods are stretching out for longer periods of time you might be perimenopausal. If you're under 45, talk to your doctor -- you may have a hormone imbalance.

Source