Is your period normal? What you need to know about your cycle and when to talk with your doc

“So, tell me: When was the first day of your last menstrual cycle?” If you’re a person with ovaries, chances are your doctor has asked you this very question — even at appointments not related to your reproductive health.

Why do doctors ask this question? There are some really compelling reasons — in addition to providing insight into your reproductive health, your period’s regularity can also be an indicator of other health conditions. Knowing what’s normal and what’s not with your cycle is an important aspect of proactively taking control of your health.

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• The duration and frequency of your menstrual bleeding is suddenly different than what’s normal for you.Period consistency is more important than period length. Having a longer monthly cycle isn't necessarily an issue — but when your period starts fluctuating and changing, it's time to seek medical advice.

• The number of days between your periods gets shorter or longer.

• You don’t bleed for a similar number of days each month.

• You experience abnormal uterine bleeding (meaning your periods get a lot heavier or a lot lighter, you bleed or spot between monthly periods, and/or you bleed following sexual intercourse). Sudden cycle changes — whether that’s spotting between periods, bleeding for more than a week, a period that suddenly stops, or extremely painful/unusually heavy periods — should be discussed with your doctor.

• You're experiencing an underlying medical issue or lifestyle trigger. Hormonal imbalances, as well as conditions like endometriosis, hypo- or hyperthyroid, PCOS, and uterine fibroids, can cause cycle irregularities and abnormal uterine bleeding. Things like going off birth control and stress can also disrupt your cycle.

• If you've gone 90 days without a period, it’s time to schedule an appointment.

Bottom line? Menstrual cycle abnormalities can be a sign of common underlying medical conditions, so it's important to keep tabs on your period health and seek medical advice if anything seems off. It’s always a good idea to start or continue the conversation about your period with your doctor. After reading this article, you’ll have some essential context to help you navigate that conversation.

There are so many aspects of health that we’re used to tracking on a daily basis: steps, macronutrients, heart rate, and so much more. Dr. Jane van Dis, an OB-GYN and a medical advisor to Modern Fertility, believes that periods should be on that list, too. “I think people deserve to have their cycles used as a vital sign and taken seriously, regardless of if they are trying to conceive,” she explains.

Why pay so much attention to your period? For one, not getting a regular period, or experiencing cycle abnormalities, can be a sign of an underlying medical condition — like endometriosis, hypo- or hyperthyroidism, and polycystic ovary syndrome (PCOS.) These conditions are chronically underdiagnosed in people with ovaries — thyroid disease affects 1 in 8 women, and PCOS and endometriosis affect 1 in 10 women (1 in 10!)

Arming yourself with the knowledge of what to look out for in terms of your period can help you effectively seek medical advice right away since you’ll know which questions to ask. Start a conversation with your doctor and advocate for yourself if you think you might have one of these conditions.

One essential part of keeping track of your cycle is knowing how long it lasts. But when we talk about how long your menstrual cycle is, we’re not just talking about how many days you’re bleeding (which is your actual “period”). We’re talking about the time it takes your body to complete a full menstrual cycle — from the first day of your period to the first day of the next period.

While most of us are taught that the menstrual cycle lasts for 28 days on average, there’s a window of what’s considered normal. A longer monthly cycle (such as 31 days between periods) or a shorter monthly cycle (such as 21 days between periods) doesn’t alone indicate any issues. However, your cycle length starts changing or your period suddenly stops coming altogether, that’s something to bring up with your doctor. Your normal is what’s key here.

Interestingly, even among reputable sources, there isn’t a consensus on how long cycles should be. The Office on Women’s Health reports that 28 days is “typical,” but cycle length can vary from month to month and periods are still “regular” if they usually come every 24 to 38 days. The Mayo Clinic, on the other hand, says that menstrual bleeding typically occurs every 21–35 days and lasts 2–7 days, but “within a broad range, ‘normal’ is what’s normal for you.”

Interesting caveat: More people think they have a 28-day cycle than those who actually do. According to one study on the accuracy of self-reported menstrual cycles, 39% of people said their average cycle length is 28 days. But after having people log their cycle lengths for several months, only 12% of cycles were actually 28 days. The actual average cycle length was about 31 days, with a standard deviation of 7.5 days. In other words: There's a substantial range of what is truly “normal,” and a lot of us are guesstimating based on what we think is normal when our doctors ask about our last periods.

A study of over 98,000 women and over 225,000 menstrual cycles confirmed that there’s a big range in what should be considered a “normal” cycle: 95% of women had cycle lengths between 20 and 40.4 days!

There is a huge range of reasons why someone might not be experiencing a regular cycle, and it’s always a good idea to talk with your doctor if that happens. Let’s break down a few common causes of irregular periods, according to the Mayo Clinic:

• Pregnancy or breastfeeding: The menstrual cycle stops during pregnancy, and hormonal changes that occur when someone is breastfeeding can delay the return of your period as well. Moreover, some people experience abnormal uterine bleeding (unusually long bouts of bleeding or bleeding at unexpected times) after enduring childbirth.

• Energy imbalance: Exercise, weight loss, weight gain, and eating disorders can all have an impact on your period. Even relatively small fluctuations in energy balance can contribute to changes in menstrual function (meaning: it’s not just extreme athletes who should be mindful of how exercise affects periods).

• Polycystic ovary syndrome (PCOS): In people with PCOS, the ovaries (and sometimes the adrenal gland) produce large amounts of androgens, aka so-called “male hormones.” The hormonal imbalance can make it difficult for eggs to mature, so ovulation and periods may happen infrequently or not at all, or you may experience abnormal uterine bleeding.

• Primary ovarian insufficiency (POI) and menopause: Your period can become more irregular as you approach menopause (going 12 months without a period). The average age of menopause in the US is 51. POI is essentially “early menopause,” which is defined as menopause before age 40.

• Pelvic inflammatory disease (PID): PID is a bacterial infection that affects the female reproductive system. It can occur when bacteria enters the reproductive tract (often through sexual contact) then spreads to the uterus and upper genital tract. It can be caused by untreated sexually transmitted infections (STIs), and can go undetected. (Many people experience no symptoms — it’s important to get tested for STIs regularly and especially before TTC). Symptoms can include irregular periods, vaginal discharge with unpleasant smell, pain in the lower abdomen, fever, diarrhea, and nausea.

• Uterine fibroids: Uterine fibroids are noncancerous growths in the uterus that appear during childbearing years. They can cause abnormal uterine bleeding between periods, prolonged or heavy bleeding during your period, as well as abdominal and pelvic pain.

A few other factors that may contribute to menstrual irregularities:

• Birth control: People are sometimes put on birth control to regulate (or eliminate) their cycles. Most people return to a regular monthly cycle within weeks or months after stopping birth control, but this can vary depending on your body and the type of birth control you were on (birth control pills, the intrauterine device, or IUD, etc.).

• Endometriosis: Endometriosis occurs when tissue that’s similar to the lining of the uterus (which is shed during your period) starts to grow outside of the uterus. It often grows on the ovaries or fallopian tubes, and sometimes on other organs. Endometriosis can cause pain during and before menstruation, heavy periods, irregular bleeding, and painful intercourse.

• Hypo- and hyperthyroidism: Your thyroid helps control your menstrual cycle. Too much or too little thyroid hormone can make your periods very light, heavy, or irregular. Thyroid disease can also cause your periods to stop for several months or longer, a condition called amenorrhea, or may result in abnormal uterine bleeding.  

• Stress: Experiencing stress can tell certain non-essential body systems to shut down. It’s not uncommon to have changes to your menstrual cycle during stressful times.

Keeping tabs on how frequently your period comes is an important part of understanding your cycle health, but should you be worried if your cycle isn’t coming like clockwork on the same day every month? Not necessarily — like we mentioned earlier, some variation in cycle length is normal and not cause for concern. In fact, only about 20% of people will have cycles that are identical in length from one month to the next. But how long your cycle lasts isn’t the only factor to pay attention to.

According to Penn Medicine, you should check in with your doctor if:

• You experience sudden changes to how often you get your period

• You bleed between periods (this is commonly referred to as spotting)

• Your period becomes unusually heavy (i.e., you have to change your menstrual product more than once every four hours)

• You bleed for more than a week

• Your periods are extremely painful

• You have gone 90 days, or the equivalent of three menstrual cycles, without getting a period (this is a condition known as amenorrhea)

Your doctor can help you take steps toward figuring out what’s causing your irregular periods and determine the appropriate treatment.

Come prepared to this appointment ready to describe why you’re concerned about your monthly cycle, as well as your reproductive goals (like if you’re planning on having kids soon or in the future). The treatment your doctor recommends will depend on your symptoms and what the doctor identifies as the underlying cause. The more info you come prepared to share, the better.

Having a detailed record (ideally of three months, at minimum) of your cycle can also be really helpful to share with your doctor. Tracking your cycle can help you figure out what’s normal for you and identify if any changes to your baseline have occurred. While there are lots of period tracking apps out there, you can even keep it as simple as writing in a journal.

When tracking your cycle, you’ll want to keep record of:

• The length of your whole menstrual cycle (counted as the first day of one menstrual period to the first day of the next one)

• The number of days you’re bleeding

• The amount of flow (Dr. van Dis recommends being specific about how many tampons, pads, cups, or discs you’re using and how frequently you're changing them)

• If you’re passing large clots

• Bleeding between periods

• Side effects, like nausea, diarrhea, cramping, headaches, or migraines

“After about three months, you should have established a pattern that will be helpful and provide valuable information to your gynecologist if you're seeing one,” says Dr. van Dis.

Staying on top of your cycle is important for anyone, but it becomes even more urgent if kids are in the future. “If someone raises concern about their cycle with their healthcare provider, there should be a prompt evaluation and a thorough workup,” Dr. van Dis says. “Evaluation and testing  can take time and, for some women, time is of the essence,” she explains.

If something is irregular with your cycle, you’ll want to know about it and seek medical advice ahead of time so you can get things on track before you start trying for kids. Here are a few ways you can check in with your menstrual cycle:

1. Tracking your ovulation: While testing your hormone levels provides you with a bird’s-eye view of your hormones and helps you track changes over time, using ovulation tests (aka ovulation predictor kits or OPKs) helps you keep an eye on the day-to-day evolution of your luteinizing hormone (LH) level. LH is the hormone that rises right before ovulation, so keying in to its changes can give you a great idea of when you might be ovulating.

2. Monitoring your cervical mucus and tracking your basal body temperature: Your cervical mucus changes in amount, color, and consistency depending on where you are in your menstrual cycle. Tracking these changes can help you pinpoint ovulation and also help you identify your fertile window (the most fertile days: the five days before ovulation and the 24 hours after ovulation when unprotected sex gives you the best chances of getting pregnant). In addition, tracking your temperature when you wake up every morning and charting it over the course of the month gives you even more knowledge about your cycle and fertility window.

3. Using an app to track your period and predict future cycles: Think of an ovulation- or period-tracking app as the culmination of all the info you have about your cycles. You can log your periods and your LH levels (based on your ovulation test results), then use that to predict future periods or your fertile window. With all this info in the palm of your hand, you’ll have all the knowledge you need to get in sync with your unique cycle.

Living in a society where periods and menstruation aren’t openly discussed means it can be much harder to know what’s normal and what’s not when it comes to your cycle (not to mention how much nuance there is in what’s considered a “normal menstrual cycle” anyway). Keeping tabs on what’s going on with your cycle, and being able to identify when things are changing, is a great way to take ownership of your health — and sharing this knowledge with others can help them do the same.

If you’re concerned about your cycle, your doctor can help you figure out a course of action that makes the most sense for you. Whether your periods are regular, irregular, or currently absent, we’re always here as a resource and to support you throughout your fertility journey. After all, there is no “one size fits all” when it comes to reproductive health — and periods are no exception.  

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How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Editorial Guidelines | Medical Review Process

Current version

March 08, 2021

Written by

Jen Lehr

Fact checked by

Jane van Dis, MD, FACOG

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About the medical reviewer

Jane van Dis, MD, FACOG

Dr. Jane van Dis is an OB-GYN, co-founder and CEO of Equity Quotient, and Medical Director for Ob Hospitalist Group.