Why Is My Period Late? 7 Health Problems That Can Delay You

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If you have a fairly predictable menstrual cycle, then you might be wondering — and with good reason — why your period is late. Maybe you felt the buildup of PMS symptoms, like bloating and headaches, only for the finale that is your period to not arrive on schedule. And when that happens it can be confusing, frustrating, and even a little bit disconcerting.

Typically, a "menstrual cycle can be anywhere from 21 to 35 days," Dr. Angela Jones, Astroglide’s resident sexual health advisor, tells Bustle, so it's likely to show up about every four weeks. And for many people, the actual period itself will then last about two to seven days, with varying degrees of flow.

That said, "some folks have irregular periods and that is just their norm," Jones says. "There are many reasons a period can be delayed. My general rule of thumb is the three month rule. If you are going more than three months without a cycle, this needs to be further investigated.”

Your doctor might find there's an underlying condition impacting your period. "For example, things such as PCOS (polycystic ovary syndrome) can cause cycles to be longer," Jones says. Or it might be due to a certain aspect of your lifestyle. Whatever the case may be, don't hesitate to ask your doctor and look into all the possible reasons. If your period is late, experts say there's a chance it's due to one of the reasons below.

1. Being Under A Lot Of Stress

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If you've been dealing with a lot of stress lately, possibly due to something going on at work or in your personal life, it can have a surprisingly big impact on your period. And may even result in it being late.

"Your hypothalamus regulates the part of brain that is responsible for regulating your period," Ashley Wood, RN, BSN, a registered nurse and contributor to Demystifying Your Health, LLC, tells Bustle. "When you’re stressed it affects your hypothalamus and can throw off your hormones," and potentially delay your period.

Once the stress passes, you might notice that your period goes back to normal, especially if you put into place a few nifty stress management techniques. But if it doesn't get back on track, let a doctor know. They can figure out if stress is to blame, or if your late period is due to something else.

2. Maintaining A Rigorous Exercise Routine

If you're training for a marathon, let's say, you may notice that the more intensely you exercise in preparation, the more it impacts your period. And the same can be true for other intense workouts.

Things like rigorous training, combined with the associated stress it puts on the body and the amount energy you exert, can disrupt your natural period cycle, Wood says, since it can cause alterations in pituitary hormones and thyroid hormones.

"Keep in mind that it takes strenuous exercise for several hours every day to produces these hormonal changes," Wood says. "So, most exercise routines don’t fall into this category."

3. Having An Unpredictable Schedule

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"Changes in your schedule can throw off your body clock, which impacts many different hormone levels in your body," Wood says. "If you frequently change work shifts, such as going from days to nights or if your schedule is erratic, it can cause variations in these different hormones and result in an unpredictable period."

If you are a shift worker, and are never going to bed or getting up at the same time, or if you simply don't have a sleep schedule at all, take note. "Typically, this means [your period will start] earlier or later than expected," Wood says, "but you don’t actually miss a period."

4. Not Getting Enough Nutrients

"The body compensates when under-fueled," Rachel Fine, registered dietitian and owner of the nutritional counseling firm To The Pointe Nutrition, tells Bustle. "In order to push through your day, the body’s resting metabolism slows to conserve energy for vital processes, like breathing and circulation."

If you're not eating enough each day, perhaps due to things like an illness or stress, you may notice that your period shows up late as a result. As Fine says, "Secondary processes not needed for individual survival, such as reproduction, get put on the back burner." If this sounds familiar, let a doctor know.

5. Dealing With A Chronic Illness

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Sometimes a chronic illness, like diabetes, can alter your menstrual cycle. So it may help to keep that in mind if you happen to be living with one. For example, as Wood says, "changes in blood sugar are related to hormonal changes. This means that poorly controlled diabetes could cause your period to be irregular."

And the same may be true for celiac disease. This chronic condition causes inflammation in your small intestine, Wood says, which can make it difficult for your body to absorb the key nutrients it needs, resulting in irregular periods.

6. Recovering From An Illness

If you're dealing with, or recovering from, a fairly serious illness, it only stands to reason that your period might be late. Things like pneumonia, for example, can result in your body rapidly losing weight resulting in nutritional deficiencies, which Wood says can cause fluctuations in your hormones.

"These can cause irregular or missed periods," she says. "Once the illness is resolved, it can take a few months for your period to return to normal."

7. Traveling

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As mentioned above, abrupt changes in your schedule — including when you go to bed and wake up — can make your period late. And the same can be true if you travel a lot.

As Wood says, "Traveling, particularly changing time zones, can also make your period a few days late. This would be related to jet lag and the impact that has on your body." So if you just got back from a big trip, or if you travel a lot for work, this is yet another factor to keep in mind.

Your period might be delayed by a few days if you're under a lot of stress, or if you've been hopping from time zone to time zone. But since a late period can also be due to something more — including pregnancy — let your general doctor or OB/GYN know so they can figure out what's up, and help you get back on track.