If your period doesn’t arrive every 28 days like clockwork, don’t freak out. While menstruation is typically portrayed as a monthly event, periods don’t always operate on a strict schedule.
There are many variations in what’s considered “normal” — and many reasons why your period timing might occasionally go awry. Learn what’s typical for your body and when something else might be going on.
What’s a normal menstrual cycle length?
The idea that a normal menstrual cycle is exactly 28 days from the end of one period to the beginning of the next is a myth. A 28-day cycle may be the “average,” but it’s not necessarily the norm.
Every body is different, so it’s no surprise that menstrual cycles differ. A menstrual cycle is considered “regular” if it’s anywhere from 24 to 38 days in length.
Getting your period more often than every 24 days, or less frequently than every 38 days, puts it into the “irregular” category. Other ways your period might be considered “irregular” include:
- Bleeding that’s very light or extremely heavy (soaking through a pad or tampon every two hours or less)
- Bleeding that lasts longer than seven days
- Spotting between periods
- Severe menstrual cramps
It’s important to note that irregular doesn’t necessarily mean unhealthy.
Causes of irregular periods
A variety of things can cause your period to change. Conditions that could result in an irregular cycle include:
- Pregnancy is the most obvious reason for missing your period. A miscarriage or breastfeeding can also change the timing of your periods or how much you bleed.
- Endometriosis results when endometrial tissue grows outside the uterus. It can cause heavy bleeding and pain.
- Polycystic ovary syndrome (PCOS) affects production of androgen hormones, which can cause irregular periods.
- Pelvic inflammatory disease is an infection that can lead to irregular bleeding and pelvic pain.
- Thyroid disorders impact the production of hormones that help regulate your menstrual cycle.
- Uterine fibroids are benign (noncancerous) growths in the uterus that can cause excessive bleeding and prolonged periods.
- Extreme weight changes, including gaining or losing significant amounts of weight, can affect your cycle.
- Excessive exercise can result in having body fat too low to support your menstrual cycle.
- Stress can lead to irregular or skipped periods.
When to see a doctor
It’s a good idea to track your periods — noting:
- When they start and end
- The amount of flow
- Any other symptoms you experience
By charting your menstrual cycle over several months, you’ll get a sense of what’s typical for you. That makes it easier to recognize when something changes in your cycle.
If your cycle is slightly longer or shorter than the 28-day average, it’s likely not a cause for concern, but check with your doctor if you:
- Bleed more frequently than every 24 days
- Bleed excessively
- Experience extreme pain with your periods
- Skip periods
They can help determine what’s causing your irregular periods and what can be done to address any underlying health issues.
