While your middle school sex education might have taught you that a period comes every 28 days, you’ve likely noticed that periods vary widely from person to person — and they can vary quite a bit for each individual person as well.
With all this variation, how do you know if your period is “abnormal” — and potentially signaling that something is wrong?
Having atypical periods is known as abnormal uterine bleeding, or AUB. What exactly constitutes “normal” and “abnormal” has long been confusing, even for health care providers. Adding to the confusion, the terminology for AUB historically included complex words like “menorrhagia” (heavy bleeding) and “oligomenorrhea” (infrequent periods).
The International Federation of Gynecology and Obstetrics (FIGO) has established criteria to help more clearly determine what qualifies as AUB. These updated definitions of normal and abnormal uterine bleeding are much more user-friendly than what were available in the past. Hopefully, these clarifications make it much easier for people to understand what’s going on in their own bodies.
An important note: If one cycle is a little delayed or you bleed a bit longer than you are used to, there probably is little reason to worry (but don’t forget to check for pregnancy!). When you notice a pattern of bleeding changes, you should probably review this with your health care team.
Is your period normal?
To determine whether your period is considered typical, consider the following questions. The FIGO criteria uses the terms “normal” and “abnormal,” so we’ll also use those terms for consistency.
How often do you get your period?
Normal: Every 24 to 38 days
Abnormal: Less than every 24 days, more than every 38 days or no bleeding at all
The frequency of your period is calculated from the first day of one period to the first day of the next period. If this is less than 24 days, you have frequent periods. If this is more than 38 days, you have infrequent periods. If you’re not experiencing any bleeding at all, this also is abnormal.
How long is your period?
Normal: 8 days or less
Abnormal: More than 8 days
The length of your period is the time from the first day of the period until bleeding stops. This used to be a very gray area with no strict definitions. But now, if you bleed for more than 8 days, that is considered a prolonged period.
How predictable is your period?
Normal: The length of your cycle varies at most by 7 to 9 days
- If you are 18 to 25, the length of your cycle should vary at most by 9 days.
- If you are 26 to 41, the length of your cycle should vary at most by 7 days.
- If you are 42 to 45, the length of your cycle should vary at most by 9 days.
Abnormal: The length of your cycle varies by 8 to 10 days or more
For example, if you have a cycle that’s 24 days, and the next cycle is 30 days, that’s still normal because that’s only a deviation of 6 days.
How heavy is your period?
Normal: A period that seems “normal”
Abnormal: A period that seems “light” or “heavy”
This used to be very difficult to accurately assess because it was based on actual milliliters of blood loss. Well, who actually measures blood loss? Now it’s very subjective and based on your interpretation of the amount of bleeding. By definition, heavy means the amount of bleeding is interfering with someone’s quality of life. This might mean leaking through tampons or pads — or having to change them frequently. What one person considers heavy, another person might consider typical.
Do you have bleeding between periods?
Normal: No spotting or bleeding between periods
Abnormal: Any spotting or bleeding — whether it is random or regular
It’s typical to not have any spotting or bleeding in between cycles. If you experience this, your provider would want to determine whether it’s happening at the same time each cycle, seems to be related to intercourse or is unpredictable. Some people regularly experience spotting midcycle around the time of egg release (ovulation), and while that’s not necessarily worrisome, it is not considered typical.
So your period is outside the typical range — now what?
If you fall into any of the abnormal categories — whether that’s based on how long, predictable, heavy or frequent your periods are — you are considered to have AUB.
It’s worth having a conversation with a health care professional about any atypical bleeding. That conversation can be with your primary care provider; it doesn’t need to be an OB/GYN — but you should talk about it with someone.
Yes, there are a lot of noncancerous (benign) reasons for AUB. But there are also some conditions that should be addressed and evaluated to make sure that there isn’t a bigger problem going on.
Possible reasons for AUB include:
- Small benign growths on the lining of the uterus (uterine polyps)
- Contraception such as an intrauterine device (IUD) or birth control pills
- A hormone imbalance, which could be caused by polycystic ovary syndrome (PCOS), obesity or thyroid problems
- Noncancerous tumors of the uterus (uterine fibroids)
- Inherited bleeding disorders
- Cancer of the cervix or uterus
A health care professional can help determine whether any of these are responsible for your bleeding — and if necessary, offer treatment.
What if you’ve already gone through menopause or are in perimenopause?
People who have gone an entire year without a period are considered to be postmenopausal. And in that case, any bleeding should not be ignored — they should seek care promptly, because bleeding could potentially be a sign of precancerous changes or cancer.
In perimenopause — the transition to menopause — periods should become lighter and less frequent. If they’re becoming heavier and more frequent, this may warrant evaluation and should be discussed with your health care team to make sure that there isn’t anything harmful going on.
What if you have a one-off period?
Say you’re having periods every 30 days, and then you have one period that comes a little bit early. That wouldn’t worry me as long as it’s a one-off thing. But if it’s becoming a persistent issue, I’d want to investigate and make sure that there isn’t anything more serious going on.
But the level of concern also depends on other factors, like your stage of life. Again, if you’re postmenopausal and haven’t had any bleeding in 5 years and start spotting, a provider should evaluate that right away.
Relevant reading
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