Here's Why You Get Your Period Twice a Month

This article was medically authored by Dr. AJ Valenson and last reviewed for accuracy on 06/15/2026.

The menstrual cycle typically lasts between 24 and 38 days. Now, we measure menstrual cycle length from the first day of this month's period to the first day of the next one. While we mentioned the average menstrual cycle length range, most women's cycles last 28 days. Of course, there are ranges of cycles, especially when younger women first start menstruating. But sudden changes in menstrual cycle length, including when your period comes twice a month, should not be considered "normal."

In some cases, two menstrual cycles in a 30-day period (medically referred to as polymenorrhea) simply means you have a cycle that’s on the shorter end. Or, it could be a temporary problem, related to stress, quality of sleep, nutritional changes or even the intensity of your exercise program. Typically, however, lifestyle-related concerns lead to fluctuating hormones and missed periods, not shorter cycles.

Instead, some conditions can affect your cycle, leaving you asking, “Why did I get my period twice in one month.” As such, the answer could be more complex. In fact, it could be a lesser-known sign of uterine fibroids, or some of the other conditions we highlight in this post.

Key Takeaways

• Menstrual cycle changes due to fibroids can be treated non-surgically via Uterine Fibroid Embolization (UFE) 
• The typical menstrual cycle lasts between 24 and 38 days
• When a period comes twice a month, it could be due to conditions such as uterine fibroids and endometriosis, or due to hormonal changes, stress or peri-menopause

Getting Your Period Twice a Month with Uterine Fibroids

Uterine fibroids are non-cancerous tumors that grow in your uterus, or attached to the organ via stalk-like growths. Still, these tumors can cause a wide array of symptoms, including painful, heavy periods or bleeding between cycles. For that reason, if you get your period twice a month, but also have pelvic pain, heavy cycles or any of these other fibroid symptoms, uterine growths could be responsible.

Why Do I Get My Period Twice a Month? Endometriosis

Uterine fibroids are non-cancerous tumors that grow in your uterus, or attached to the organ via stalk-like growths. Still, these tumors can cause a wide array of symptoms, including painful, heavy periods or bleeding between cycles. For that reason, if you get your period twice a month, but also have pelvic pain, heavy cycles or any of these other fibroid symptoms, uterine growths could be responsible.

Pre-Menopausal Cycle Changes

When a woman enters menopause, that means she hasn’t had a period for one full year. But, in the months or years leading up to menopause, a time period referred to as perimenopause, your cycle goes through many changes. In some months, you may not have a period at all. (Or your flow could be very light.) At other times, your cycle may shorten, so it seems like you’re menstruating more than once in a 30-day period.

Hormonal Changes

If your thyroid isn’t working properly, this could impact your menstrual cycle. After all, the thyroid gland regulates hormone levels in your body. So, if it’s under or overactive, your hormones will fluctuate and your cycle may change soon afterward.

Similarly, if you suddenly gain weight, your cycle may change. And that’s because weight gain can contribute to changes in your estrogen levels, which could alter when and how your period shows up.

Stress

As many women learned during the COVID 19 pandemic, stress and changes in your sleep cycle impact your menstrual cycle. During the pandemic lockdowns, many women got their period twice a month—or even more often. Fortunately, when stress is a trigger, your body usually resets once you can relax or adjust to your new normal.

Recently, we learned of another surprising why the pandemic may have affected women's periods. A study in The British Medical Journal revealed that getting vaccinated for COVID can affect your period timing. Specifically, the researchers learned that women's periods started about one day late, on average, after receiving the first dose of a COVID vaccine. Then, if the women received two doses within one menstrual cycle?

Well, the changes magnified. In this case, women's periods began four days late on average. But 13 percent of the women in the study experienced period delays of eight or more days. Meaning, the following month, those women may have experienced a period twice a month, since the delays appeared to be temporary, and most women's cycles returned to normal after one month. Additionally, many women reported having heavier periods after their COVID vaccines, but this study did not examine that reported effect.

As you can tell, so many things can make your period come twice a month. Sometimes, it’s hard to tell what’s causing the trouble on your own. So, how can you know when to worry?

Here’s the deal: you’re the person who best understands your body. For that reason, any cycle change that seems unusual to you is worth mentioning to your doctor. Then, if uterine fibroids are the reason your period comes twice a month, we invite you to request a consultation at one of our seven locations in the regions surrounding Houston and Dallas. We’re here to discuss your symptoms and review all your fibroid treatment options.