What Causes a Woman to Menstruate Twice in One Month?

Common and Rare Causes of Frequent Periods

Getting two periods in one month is often due to something simple and harmless. For some, it may even be their norm. The typical menstrual cycle is 28 days, but 24- to 38-day cycles fall within the normal range.

Occasionally shorter menstrual cycles can be due to stress, perimenopause, forgetting your birth control pill, and pregnancy.

However, frequent short menstrual cycles can sometimes indicate an underlying health problem that should be evaluated. Thyroid disease, endometriosis, uterine fibroids, and cancer can cause shorter menstrual cycles or mid-cycle bleeding.

This article looks at what causes a woman to menstruate twice a month. It also explains the various conditions that can cause irregular menstrual cycles and when to see your healthcare provider.

Fluctuating Hormones

Period frequency, how many days it lasts, and how much you bleed are all influenced by your body’s hormone levels. These levels fluctuate throughout your life.

The textbook average menstrual cycle is 28 days. However, normal menstrual cycles can be as short as 24 days and as long as 38 days.

People with cycles on the low end of normal may get 15 periods a year. In that case, menstruating twice in a calendar month will happen about three times a year.

Shorter cycles are also more common when you first start menstruating and as you approach menopause.

During your teen years, cycles are often irregular because of all the hormone changes that are taking place. Your cycles may normalize in your 20s or 30s, only to once again become irregular in your 40s and early 50s as you make the transition to menopause.

 Hormonal Changes Average Age Age Range
First period  12 8-16
Perimenopause  41-43 Late 30s-mid-40s
Menopause 51 Late 40s-early 50s
Early menopause -- 40-45
Premature menopause -- Under 40

Pregnancy

Irregular bleeding is common in early pregnancy. If you are sexually active and have menstrual bleeding twice in one month, you could be pregnant.

Spotting can be caused by implantation, ectopic pregnancy, and complications in early pregnancy.

If you suspect you may be pregnant, take an at-home pregnancy test. If negative, wait a few days before retesting.

Puberty

The average age to start menstruating is 12, but that’s not a rule. A first period can come anywhere between 8 and 15.

For the first few years, your periods might be irregular because of constantly shifting hormones. Teenage menstrual cycles can last anywhere from 21 to 45 days. This can cause two periods in one month.

These early fluctuations are usually not a cause for concern. However, if you don’t get more regular over time, talk to a healthcare provider.

If there’s no underlying condition causing frequent or irregular periods, a provider may prescribe oral contraceptives (birth control pills) to regulate your cycle.

Verywell / Ellen Lindner

Perimenopause

Perimenopause happens when you are transitioning to but have not yet reached menopause. (Menopause begins when you haven’t had a period for 12 months in a row.)

During this time, your estrogen levels drop. That can make your cycle irregular and your periods more (or less) frequent—possibly causing two periods in one month.

The blood flow may also be shorter or longer, lighter or heavier.

Most people with female reproductive organs start this phase between their late 30s and mid-40s. The process generally lasts for about eight to 10 years before menopause begins.

Some people have early (before age 45) or premature (before age 40) menopause. Changes in period frequency can be a sign that you’re entering one of these phases.

If period changes are related to perimenopause, you might be able to regulate them with birth control pills, patches, or rings.

Bleeding After Menopause

Vaginal bleeding after menopause is not normal. It can be a sign of serious disease, including endometrial cancer. Call your healthcare provider right away if you’re postmenopausal and have any vaginal bleeding or abnormal discharge.

Thyroid Problems

Your thyroid gland and the hormones it makes are important for regulating your menstrual cycle.

Both too much thyroid hormone (hyperthyroidism) or not enough (hypothyroidism) can cause shorter menstrual cycles.

With hypothyroidism, your periods can be really heavy or more frequent, such as two periods in a month. You may need to change your pad, tampon, or cup every hour or double up your protection (such as wearing a tampon and pad). Your periods may also last longer than a week.

Hyperthyroidism is more commonly associated with lighter, less frequent periods. However, too much thyroid hormone can also shorten the luteal (post-ovulation) phase. This may cause you to menstruate twice in one month.

Skipping or Stopping Birth Control

Oral contraception (birth control pills) suppresses your normal menstrual cycle with hormones that keep your body from ovulating.

Birth control pills usually come with a three-week supply of pills with hormones followed by a week of pills without any hormones (placebos). The lack of hormones during the placebo week triggers your period.

The same thing can happen when you go off of the pill or even miss just a pill or two. This can happen even if you’ve had a recent period, leading to two periods in one month.

Your body can also react this way if you make a mistake with another form of hormonal birth control like the birth control patch or the ring.

The right way to restart birth control after missing one or more doses depends on the type. Always read the information that comes with your pills. You can also ask your provider or pharmacist what to do if you forget a pill.

Forget a Pill?

If you miss a pill, you need to use a backup method of contraception or emergency contraception to avoid an unintended pregnancy.

Endometriosis

Endometriosis is a medical condition that causes tissue that’s similar to the endometrium to grow in other parts of the body.

The main symptoms of endometriosis are painful periods, excessive bleeding, and short menstrual cycles—which could mean having two periods in one month.

People with endometriosis have extra and more severe periods in part because the endometrium has overgrown, which means there’s more of it to be shed.

If you have endometriosis, you might also have bleeding and pain when you ovulate because the tissue can stick to the ovaries and form cysts.

Other symptoms of endometriosis include:

  • Menstrual cramps that do not get better with over-the-counter anti-inflammatory drugs
  • Nausea and vomiting
  • Excessive gas
  • Diarrhea
  • Chronic pelvic pain
  • Fatigue
  • Headaches or migraines
  • Leg pain
  • Pain during vaginal penetration
  • Painful bowel movements
  • Difficulty getting pregnant

Endometriosis can sometimes be managed with low-dose birth control pills or other hormone therapies.

Surgery to remove the lesions may help, but the tissue often comes back. Some people with endometriosis have their uterus and/or ovaries removed (hysterectomy and oophorectomy).

Uterine Polyps or Fibroids

Uterine polyps and fibroids are non-cancerous growths on the uterus.

Uterine polyps (also called endometrial polyps) are soft growths in the uterus or cervix. They can be as small as a sesame seed or larger than a golf ball.

You can have one or multiple polyps, which are usually not cancerous. They’re more common with age and rare in people under 20.

Symptoms of uterine polyps include:

  • Post-menopausal bleeding or spotting
  • Infertility
  • Bleeding after vaginal penetration

Uterine fibroids are growths in the muscle tissue rather than the endometrium. They’re also called leiomyomas or myomas.

Fibroids can be inside or outside the uterus. As with polyps, you can have one or several.

Symptoms of uterine fibroids include:

  • Bloating and swelling in the abdomen
  • Frequent urination and being unable to empty your bladder
  • Pain during vaginal penetration
  • Lower back pain
  • Constipation
  • Vaginal discharge

Both polyps and fibroids can cause problems with your menstrual cycle. You may have more frequent periods (including two periods in one month), longer and heavier periods, and bleeding between periods.

The treatment for polyps and fibroids ranges from symptom management and hormonal therapies to surgical removal of the growths. In more serious cases, people need to have a hysterectomy.

Uterine growths can also affect your fertility and may even cause miscarriages.

Weight Gain or Obesity

Rapid weight gain can throw off your cycle. That’s because it affects the part of your brain that regulates hormones (the hypothalamus). This can lead to hormonal fluctuations that may cause two periods in one month or infrequent periods.

Obesity has a complex relationship with menstruation. High levels of fat (adipose tissue) can upset the balance of sex hormones and lead to excess estrogen.

Too much estrogen can make you have short menstrual cycles and more periods. Hormonal imbalances can also cause heavier bleeding, more cramps, and longer-lasting pain during your period.

Menstrual changes related to weight are most severe when the extra fat is mostly around the belly.

Losing weight and maintaining a healthy weight for your body can help keep your menstrual cycle regular. If you need help losing weight, talk to your provider about your options.

Stress

Changes in your day-to-day routine can affect your menstrual cycle. Certain habits and situations might make you have two periods in one month or get your period early.

Perceived stress can throw off the hypothalamus and lead to the release of excess stress hormone (cortisol).

All that extra cortisol changes your body’s ability to regulate hormones, which can lead to irregular menstrual cycles and either more or fewer periods.

Typically, getting back to your normal routine will also get your cycle back on track.

Pelvic Inflammatory Disease

Pelvic inflammatory disease (PID) is an infectious illness. It occurs when normal vaginal bacteria or sexually transmitted infections (STIs)—especially chlamydia and gonorrhea—move from the vagina up to the:

The risk of PID is higher when:

PID can cause irregular menstrual cycles, including two periods in one month or spotting and cramping between periods.

Other symptoms of PID include:

Repeated bouts of PID can cause scarring on the fallopian tubes that can lead to chronic pelvic pain, ectopic pregnancy, and infertility.

It’s important to get PID treated as soon as possible. While antibiotics can clear up the infection, they won’t heal the damage to your reproductive organs.

Cancer

It’s not as common as other reasons, but menstrual changes (including two periods in one month) can sometimes be a sign of cancer.

Cancers of the reproductive organs, including the uterus, cervix, and ovaries, can change your hormones and menstrual cycle.

Uterine cancer can cause you to have periods more often. Cervical and ovarian cancers are more often associated with long and heavy periods rather than more frequent periods.

Uterine Cancer

Two types of cancer are possible in your uterus:

  • Endometrial cancer: Tumors develop in the uterine lining (by far the most common type).
  • Uterine sarcoma: Cancer develops in the wall of the uterus (extremely rare).

Either type of cancer can cause more frequent periods that might also be very long and heavy—especially if you’re over the age of 40.

These cancers can also cause bleeding between periods and spotting or bleeding after menopause.

Other symptoms of reproductive cancers include:

  • Pain or cramping in the lower abdomen/pelvis
  • Unexplained weight loss
  • Thin, clear, or white vaginal discharge after menopause

The treatment for uterine cancer depends on the type you have and how healthy you are. A few options include:

When to See a Healthcare Provider

While some of the causes of frequent periods are not serious and don’t need treatment, don’t assume that’s the case if you have two periods in one month.

Call your provider if:

  • Your period becomes irregular, especially if it’s sudden or without an obvious cause (like a missed birth control pill).
  • Your periods are less than 21 days apart.
  • You have a period that lasts more than seven days.
  • You have an unusually heavy or painful period.
  • You bleed between periods.
  • You bleed at all after menopause.

By doing so, you may catch a problem early and start the treatment you need. If there’s not a problem, your provider can put your mind at ease and help figure out what you need to do to get your cycle back on track.

Tracking Your Period

It can be helpful to show your provider a record of when your most recent periods started and stopped. As you track your period, also note symptoms such as pain, heavier blood flow, fatigue, weight gain, or fever. This information can help your healthcare provider narrow down the possible causes of your period changes.

Summary

Shorter menstrual cycles are not necessarily a sign that something is wrong. For some people, they’re normal. However, if you’re usually regular and suddenly have two periods in one month—and the cause isn’t obvious—talk to your provider.

Many things can make your period come more often than usual. Natural hormone fluctuations can cause this, as can missing a birth control pill and lifestyle factors like being overweight or stressed.

Having your period twice in one month could also be a sign of a medical condition that needs treatment.

Frequently Asked Questions

  • Do you ovulate if you get your period twice a month?

    You may not ovulate if you have short menstrual cycles and get two periods in one month. Research has shown that this is particularly true if your cycle is fewer than 25 days.

  • Could you be pregnant if you bleed before your period is due?

    In about 15% to 20% of pregnancies, spotting results from the fertilized egg attaching to the lining of the uterus (implantation bleeding). The blood flow is usually much lighter than your normal period.

  • Are irregular periods always a concern?

    No. Some people always have irregular cycles, very short cycles, or spotting during ovulation. This may be normal for you, but your healthcare provider should determine that.

31 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Department of Health and Human Services Office on Women’s Health. Your menstrual cycle.

  2. Icahn School of Medicine at Mount Sinai. Vaginal bleeding in early pregnancy

  3. Icahn School of Medicine at Mount Sina. Vaginal bleeding between periods

  4. Icahn School of Medicine at Mount Sinai. Vaginal bleeding – hormonal.

  5. National Institute of Child Health and Human Development. What are the common treatments for menstrual irregularities?.

  6. American College of Obstetricians and Gynecologists. Perimenopausal bleeding and bleeding after menopause.

  7. Department of Health and Human Services Office on Women’s Health. Early or premature menopause.

  8. Delamater L, Santoro N. Management of the perimenopauseClin Obstet Gynecol. 2018;61(3):419-432. doi:10.1097/GRF.0000000000000389

  9. American Cancer Society. Signs and symptoms of endometrial cancer.

  10. Department of Health and Human Services Office on Women's Health. Thyroid disease.

  11. Jacobson MH, Howards PP, Darrow LA, et al. Thyroid hormones and menstrual cycle function in a longitudinal cohort of premenopausal women. Paediatr Perinat Epidemiol. 2018;32(3):225–234. doi:10.1111/ppe.12462

  12. University of Iowa Hospitals & Clinics. Birth control pill fact sheet.

  13. Planned Parenthood. Will missing my birth control mess up my period?

  14. National Women’s Health Network. How does endometriosis affect my menstrual cycle?.

  15. Endometriosis Foundation. Endometriosis symptoms: abnormal periods.

  16. Brigham and Women's Hospital. Uterine polyps overview.

  17. Nijkang NP, Anderson L, Markham R, Manconi F. Endometrial polyps: pathogenesis, sequelae and treatment. SAGE Open Med. 2019;7:2050312119848247. doi:10.1177/2050312119848247

  18. Tarney CM, Han J. Postcoital bleeding: a review on etiology, diagnosis, and management. Obstet Gynecol Int. 2014;2014:192087. doi:10.1155/2014/192087

  19. American College of Obstetricians and Gynecologists. Uterine fibroids: frequently asked questions.

  20. Ko KM, Han K, Chung YJ, Yoon KH, Park YG, Lee SH. Association between body weight changes and menstrual irregularity: the Korea National Health and Nutrition Examination Survey 2010 to 2012. Endocrinol Metab (Seoul). 2017;32(2):248-256. doi:10.3803/EnM.2017.32.2.248

  21. Kafaei-Atrian M, Mohebbi-Dehnavi Z, Sayadi L, Asghari-Jafarabadi M, Karimian-Taheri Z, Afshar M. The relationship between the duration of menstrual bleeding and obesity-related anthropometric indices in studentsJ Educ Health Promot. 2019;8:81. doi:10.4103/jehp.jehp_24_18

  22. Bae J, Park S, Kwon JW. Factors associated with menstrual cycle irregularity and menopause. BMC Womens Health. 2018;18(1):36. doi:10.1186/s12905-018-0528-x

  23. Vigil P, Meléndez J, Soto H, Petkovic G, Bernal YA, Molina S. Chronic stress and ovulatory dysfunction: implications in times of COVID-19. Front Glob Womens Health. 2022;3:866104. doi:10.3389/fgwh.2022.866104

  24. University of Michigan, Michigan Medicine. Symptoms of pelvic infection.

  25. American Academy of Family Physicians. Pelvic inflammatory disease.

  26. American College of Obstetricians and Gynecologists. Pelvic inflammatory disease (PID).

  27. Cleveland Clinic. Uterine cancer.

  28. University of Pennsylvania Medical School. Irregular periods: Why is my period late?

  29. Nemours Foundation. Irregular periods.

  30. Wesselink AK, Wise LA, Hatch EE, et al. Menstrual cycle characteristics and fecundability in a North American preconception cohort. Ann Epidemiol. 2016;26(7):482-487.e1. doi:10.1016/j.annepidem.2016.05.006

  31. American College of Obstetricians and Gynecologists. Bleeding during pregnancy.

By Denise Witmer
Denise Witmer is a freelance writer and mother of three children, who has authored several books and countless articles on parenting teens since 1997.