Factors That Can Affect Your Menstrual Cycle

calendar with period start date marked
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Most people think of periods as a predictable part of a woman's life. As a biological woman, you will likely develop a period; however, when and how frequently it occurs can vary even if you've been getting your period for years.

Life Stage Factors

During the first year or so of having your period, your body may be working at getting into a routine. For example, you might have your first period and then not have another one for a few months. Or, you might have a few periods and skip one a few months down the road.

If you are premenopausal, your period may occur less frequently until it ultimately ceases—known as menopause.


Pregnancy, ectopic pregnancy, and miscarriages can also affect when your period comes. If you think you may be pregnant you can take an at-home pregnancy test, any positive results should be followed up with a doctor's appointment.

Lifestyle Factors

Even while your body is establishing your normal pattern, or well after you've developed a normal routine, there are other things that can affect your period. For example, if your body has too little fat on it or you are exercising too much, your period can stop or your cycle can be longer than average. Seek medical support if you have an eating disorder or believe your period may be affected by disordered eating.

Stress can also affect your period. If you are going through a particularly stressful time, your period may stop or change from what is normal for you. While this usually doesn't cause long-term period problems, try and reduce your stress if it is affecting your period. If the stress is too much for you to handle on your own or continues for a long time, talk to a therapist or trusted friend or family member.

Health Conditions

Physical illness can also affect your period. A bad cold or flu may be enough to throw your period off that month. Likewise, a major illness can certainly cause you to skip your period. Make sure you alert your doctor if your period is consistently irregular.

Certain medical conditions can also affect your period. Hypothyroidism, or an underactive thyroid, can make your period irregular, with cycles being heavier and less frequent. Other chronic conditions that put stress on your body over a long period of time can also cause your period to fluctuate.

You might want to talk with your health care provider about a condition called a bleeding disorder if you have very heavy menstrual periods or have ever had problems with the following things:

  • Easy bruising
  • Frequent or prolonged nosebleeds
  • Prolonged or heavy bleeding after minor cuts, dental work, childbirth, or surgery

The most common bleeding disorder in girls and women (von Willebrand disease or VWD) runs in families, so your mother, sister, female cousins, or aunts also might have some of the signs listed above.

Heavy periods can also be caused by uterine fibroids, non-cancerous tumors that occur within the uterus. Heavy periods, painful, or irregular periods may also be the result of endometriosis—a reproductive condition where tissue similar to the lining of the uterus is found outside of the uterus. Polycystic ovarian syndrome (PCOS) can cause irregular periods as well, with some women only menstruating several times per year.

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Article Sources

  • The National Women's Health Information Center