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Published on December 21, 2011

Women’s Health: Common Causes of Irregular Menstrual Cycles

Women’s bodies are forever changing. From time to time, every woman suspects that her menstrual cycle is abnormal for one reason or another. It’s important to remember that each woman’s cycle is different, so your “normal cycle” may not be the same as your best friend’s “normal cycle.” There are, however, some common reasons for a period to be irregular.

“Because each woman’s cycle is different, and because there are so many factors that cause an ‘irregular’ cycle, it can sometimes be hard to pinpoint an exact reason for the irregularity,” says Thomas J. Bader, M.D., chairman of the Department of Obstetrics and Gynecology at Crozer-Chester Medical Center. “Periods are often irregular during the first couple of years of menstruation. This is because the body is still developing the delicate hormonal balance that leads to a regular cycle. Another common cause of an irregular or missed period is pregnancy.”

If you are not pregnant, WebMD lists these other common causes of an irregular period:

  • Excessive weight loss or gain: although low body weight is a common cause of missed or irregular periods, obesity also can cause menstrual problems
  • Eating disorders, such as anorexia or bulimia
  • Increased exercise: missed periods are common in endurance athletes.
  • Emotional stress
  • Illness
  • Travel
  • Medicines such as birth control methods, which may cause lighter, less frequent, more frequent, or skipped periods or no periods at all
  • Hormone problems: this may cause a change in the levels of the hormones that the body needs to support menstruation
  • Illegal drug use
  • Problems with the pelvic organs, such as imperforate hymen, polycystic ovary syndrome, or Asherman’s syndrome
  • Breastfeeding: many women do not resume regular periods until they have completed breastfeeding.

“If, for any reason, your period is irregular, you should contact your healthcare provider,” says Rebecca Choitz, CNM, director of Midwifery Services for Crozer-Keystone Health System. “It’s always best to be proactive when it comes to your health ― something women can often forget when running their busy lives. Getting something checked out can help to prevent serious health conditions later on down the road.”

So, if your cycle is irregular, how can you tell when you're about to get your period? Below are some clues your body may give you, according to the National Institutes of Health:

  • Back cramps or stiffness
  • Heavier breasts or breast soreness
  • Headaches
  • Acne breakouts
  • Disturbed sleep patterns
  • Mood swings
  • Bloating

“Women may also find that their menstruation cycle is changing before menopause,” says Joseph G. Grover, M.D., chairman of the Department of Obstetrics and Gynecology at Delaware County Memorial Hospital. “Women can experience age-related menstrual changes as early as their 30s.”

According the Mayo Clinic, a woman has reached menopause when she has not had a period for one year. Some of the changes that women can experience include:

  • A change in periods - shorter or longer, lighter or heavier, with more or less time in between
  • Hot flashes and/or night sweats
  • Trouble sleeping
  • Vaginal dryness
  • Mood swings
  • Trouble focusing
  • Less hair on head, more on face.

For information about Crozer-Keystone’s obstetric and gynecologic services, or to find a physician who is right for you, call 1-800-CK-HEALTH (1-800-254-3258) or visit

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