Starting at puberty, periods become a regular part of a woman's life. The shedding of uterine tissue and blood typically happens once per cycle — roughly once a month. Each cycle ends with a menstrual period.
Some women get more than one period per month, for a variety of reasons. While menstruating twice in a month can be annoying, it doesn't necessarily signal a problem.
Understanding the Menstrual Cycle
The menstrual cycle is the monthly series of hormone-driven processes that prepare a woman's body for pregnancy. The average cycle lasts 28 days, but it can range from 21 to 38 days.
During each menstrual cycle, the uterine lining thickens to prepare for a possible pregnancy, and one egg matures in its follicle. During ovulation, around halfway through the cycle, the ovary releases the mature egg, which travels down the fallopian tube to the uterus. If a pregnancy doesn't occur, the uterine lining sheds in a menstrual period.
The entire cycle is regulated by estrogen and progesterone — hormones that are released by the ovaries under the direction of the hypothalamus and pituitary gland in the brain.
Possible Causes of 2 Menstrual Periods in 1 Month
There are many possible reasons why you might have two menstrual periods in a month. The simplest explanation is that your menstrual cycle is closer to 21 days, in which case the cycle will end before the calendar month does. "If your cycle is on the shorter side, it is entirely possible to have two periods within one month," says Anthony C. Monteiro, DO, an obstetrician gynecologist at RWJ Barnabas Health in New Brunswick, New Jersey.
Other reasons range from lifestyle changes to medical conditions.
Lifestyle Changes and Stress
Any major changes to your routine can throw the menstrual cycle out of whack. Shifts in diet, exercise, sleep, or weight can all influence cycle length.
Stress is a big contributor to menstrual irregularities. When the body is under stress, it releases the hormone cortisol, which can disrupt the normal release of estrogen and progesterone. That hormonal shift can lead to more or less frequent periods.
Hormonal Imbalance
Estrogen and progesterone play big roles in the menstrual cycle. Rising estrogen levels in the middle of the cycle trigger the release of luteinizing hormone (LH) from the pituitary gland, which causes an egg to mature and ovulation to occur. Both estrogen and progesterone prepare the uterine lining for a possible pregnancy. If no pregnancy happens, levels of these hormones drop and a period starts.
An imbalance in levels of estrogen and progesterone, whether from age, a medical condition, or medication, can make periods come more frequently than usual.
Birth Control and Medications
A pack of birth control pills contain a mix of active (containing estrogen and progesterone) and inactive pills. Periods come on days when you’re taking the inactive pills. Continuous birth control pills, which are mainly active pills, reduce the number of periods or eliminate them entirely. "However, it is possible for an individual to have unexpected or bothersome bleeding while on birth control, in which case they should check in with their doctor," Dr. Monteiro says.
Some women bleed a little while taking active pills. This isn't a period. Doctors call it breakthrough bleeding.
Starting, stopping, or changing to a different form of hormonal birth control can lead to more or fewer periods because it disrupts the normal menstrual cycle. Women may have irregular periods for up to six months after they go off the pill.
Other forms of hormonal birth control, like the intrauterine device (IUD), injections, and implants can also lead to irregular periods, says Rhiana Saunders, MD, a reproductive endocrinologist and infertility specialist with Aspire Houston Fertility Institute in Texas. So can some other types of medicines, like anti-seizure drugs and antipsychotics.
Age-Related Factors
Both puberty and perimenopause are times when hormone levels fluctuate. It's common to have irregular or extra periods during both of these life transitions, says Monteiro.
When the egg supply dwindles heading into menopause, the ovaries become less responsive to signals from the brain. As a result, women may "ovulate at shorter intervals or at chaotic intervals, and have unpredictable bleeding patterns," says Dr. Saunders.
Medical Conditions
Some conditions cause extra periods or longer bleeding. "This is typically due to disruptions to hormones or the endometrial lining," says Monteiro.
Medical conditions that affect menstrual periods include:
Polycystic Ovary Syndrome (PCOS)PCOS causes small, fluid-filled sacs to form on the ovaries.
Uterine Fibroids and Polyps Fibroids are noncancerous growths in the lining of the uterus that cause heavy or unpredictable periods and pain.
Endometriosis In endometriosis, tissue that resembles the lining of the uterus grows in other parts of the abdomen.
Thyroid Disorders The thyroid gland helps control menstrual cycles. A thyroid disorder that leads to excessive or inadequate thyroid hormones can make periods irregular.
When to Consult a Healthcare Professional
Two periods in a month usually isn't cause for concern, especially if it happens consistently and doesn't come with other symptoms. "If this is new for you or your cycles are usually regular and now suddenly you're bleeding more frequently, it could be worth checking in with a doctor," Monteiro says.
Symptoms to Watch For
Let your doctor know if you get symptoms like these with extra periods:
Very heavy bleeding
Severe cramps or pelvic pain
Unexplained weight gain or loss
Dizziness or fainting
Abnormal or smelly vaginal discharge
Prevention and Self-Care Strategies
The only way to prevent extra periods is by taking a hormonal birth control method like the pill or IUD. But following a healthy lifestyle is good for your health overall, says Saunders.
Monteiro and Saunders suggest trying the following strategies:
Eat a nutrient-dense diet that's heavy in foods like fruits, vegetables, whole grains, and lean protein
Do a mix of aerobic and strength-training exercises
Avoid smoking and alcohol
Get a minimum of seven hours of sleep a night
Manage stress with relaxation techniques like meditation, deep breathing, or yoga
Also, keep a close watch on your menstrual cycles. If you notice something's not right, tell your doctor and go in for an evaluation. "Get to the root of the problem, and then focus your treatments on that issue," Saunders says.
The Takeaway
Periods typically come once in each menstrual cycle, which averages about 28 days.
Some women get two periods in a month because their cycles are shorter than usual.
Other possible causes of two periods in a month are hormone imbalances, medical conditions like PCOS and uterine fibroids, and age-related factors.
Hormonal birth control can reduce the number of periods you have in a month.
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John Paul McHugh, MD, is an obstetrician-gynecologist and lifestyle medicine specialist in southern California. He has always placed wellness at the center of his work, in both delivering babies and improving practice standards. Dr. McHugh believes that bringing lifestyle medicine to the center of health and wellness empowers patients to make the change they seek and enjoy the benefits of true wellness.
He is a graduate of Harvard Medical School and the Massachusetts Institute of Technology and a fellow of the American College of Lifestyle Medicine. He served as a department chair at Scripps Mercy Hospital in San Diego and is now the chair-elect for the American College of Obstetricians and Gynecologists for California.
He has published several articles in the American Journal of Lifestyle Medicine and served as a peer reviewer for many articles. He contributed to the first textbook of lifestyle medicine in women's health: Improving Women's Health Across the Lifespan.
Stephanie Watson is a freelance health writer who has contributed to WebMD, AARP.org, BabyCenter, Forbes Health, Fortune Well, Time, Self, Arthritis Today, Greatist, Healthgrades, and HealthCentral. Previously, she was the executive editor of Harvard Women’s Health Watch and Mount Sinai’s Focus on Healthy Aging. She has also written more than 30 young adult books on subjects ranging from celebrity biographies to brain injuries in football.
