How Your Period Changes As You Age

From easier cramps to a heavier flow, here's a guide on what to expect in your 20s, 30s, and 40s—and when a change to your cycle might be a sign of something serious.

We're just taking a guess here, but your period is probably not your favorite monthly event—especially when it gets all weird on you. One month it's late, the next it's early; you're used to a flow lasting four days, then all of a sudden it sticks around for a full week. Cramps sideline you when you're caught without pain meds, but once you're stocked up on ibuprofen, you don't feel a twinge of discomfort.

Changes to your menstrual cycle like these are hard to predict. Because as you get older, your period will keep adjusting and evolving, thanks in part to normal age-related hormonal changes as well as experiences such as pregnancy and perimenopause, or the transition to menopause, according to the National Library of Medicine.

Here's a better idea of what to expect through the years (as well as what might be a sign that something isn't right).

In Your 20s

If you spent most of your teen years struggling with an unpredictable period (you know, the no-show kind that then made surprise appearances at the worst times), we've got great news: at this point in your life, your flow will likely become more consistent.

Why? It's very typical for young girls not to ovulate regularly, said Lauren Streicher, MD, a Chicago-based ob-gyn and author of Sex Rx: Hormones, Health, and Your Best Sex Ever. And without regular ovulation, your periods will be more erratic. On the other hand, when your cycle evens out and comes more or less monthly, you'll also start experiencing PMS, cramps, and breast tenderness. If you weren't used to dealing with these side effects every month, it can be something of an unpleasant surprise.

Another major menstruation change that tends to happen in your 20s has to do with going on birth control. This is the decade many people decide to start taking hormonal contraception. Going on the pill will likely trigger changes to your usual flow. Think: lighter and more regular periods, less cramping, and reduced PMS symptoms per the American Society for Reproductive Medicine.

In fact, the pill (or another form of hormonal contraception, like the hormonal IUD or Depo-Provera, the birth control shot), according to the National Library of Medicine, can even cause your periods to disappear. Birth control pills prevent ovulation, and without ovulation, there's less or no uterine lining buildup that has to be shed.

In Your 30s

For the most part, menstruation should be pretty predictable and consistent in this decade, said Dr. Streicher. Symptoms such as a suddenly heavier flow or more intense pain than your usual cramps may be a sign of a bigger issue. For example, fibroids, which are benign growths in the lining of the uterus and can leave you with heavier bleeding, are more common after age 30, according to the Office on Women's Health. And endometriosis, which is often marked by pain that might last all month, is also more common in those in their 30s or 40s, per the Office on Women's Health.

Another game-changer that may arise in your 30s? Having babies. Your period doesn't usually come back until six weeks after delivery if you're not breastfeeding, said Sheryl Ross, MD, an ob-gyn in Santa Monica, California, and author of She-ology: The Definitive Guide to Women's Intimate Health. Period. "And if you decide to breastfeed, your period will not return until you stop or reduce the amount of times you're nursing."

What's more, delivering a kid may lead to long-term shifts to your cycle. "Many women will tell you that after they've gone through pregnancy, their cramps get better," said Dr. Streicher. "That can be caused by a number of things, but since the cervical opening becomes a little bigger, the flow comes out without requiring as strong uterine contractions."

In Your 40s

Your 40s may mark the beginning of perimenopausal hormonal fluctuations, which are precursors to menopause. During this time, which is generally about seven years before menopause but can sometimes last as long as 14 years, according to the National Institute on Aging, your body preps for the menstruation finish line (which often happens in your 50s).

Normal hormone changes cause ovulation to be more irregular, and estrogen level fluctuation means you could start experiencing missed periods, a heavier flow, or spotting between periods. "The thing I always say about perimenopause symptoms is the one thing that's predictable is that nothing is predictable," said Dr. Streicher. Just don't forget, that even if ovulation is erratic, you can still get pregnant. A woman isn't in menopause until her periods have ceased for at least a year.

Whatever your age, remember that your period offers a lot of insight into overall health. So if you experience any period changes, it's a good idea to check in with your healthcare provider, said Dr. Ross. Highly irregular periods or drastic changes to your flow may be a sign of a number of other (treatable) health concerns, according to the American Society for Reproductive Medicine, such as benign or cancerous growths or hyperplasia (overgrowth of the lining of the uterus).

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