Some of these differences are completely normal, while others may require a health care professional's attention. The key is to be aware of any changes. Talk to your health care professional if you have concerns with your menstrual cycle or if you have symptoms that interrupt your daily living.

Do any of these questions relate to your experience? If you're not sure, start using the cycle calendar to chart differences that might take place from month to month. You may even find that your cycle affects your body throughout the month in more ways than just your period.

• What if my period stops but I'm sure I'm not pregnant?
  The absence of menstruation is called amenorrhea. While the most common cause of amenorrhea is pregnancy, it can also be a common symptom of underlying reproductive system conditions,^{4. Danforth's Obstetrics & Gynecology, p. 625A, 640A,B} or due to excessive weight gain or loss.^{7. Dorland's Medical Dictionary, p. 59} Talk to your health care professional about your symptoms.
  
  
• What if I have a period each month, but it's really light or short?
  Regularly timed menstruation cycles that have a decreased amount of bleeding (also known as hypomenorrhea) ^{10. Berek, p. 159 A} may occur in women on oral contraceptives.^{2. Mishell, p. 904A} Women on the Pill experience a withdrawal bleed, which usually lasts 3 to 4 days, as opposed to a normal menstrual period, which lasts, on average, 5 days, and averages less blood loss than a normal period.^{2. Mishell, p. 904A} However, it can be normal for women not on the Pill to have light or short periods, too. Talk to your health care professional if you're concerned about light or short periods.
  
  
• What if my period is infrequent?
  Also called oligomenorrhea, infrequent menstruation is defined as having irregularly timed episodes of bleeding, which usually occur at intervals of more than 35 days.^{10. Berek, p. 159 A} Usually, it is caused by common factors such as age, hormones, or infection, but it can possibly be associated with other factors such as pregnancy or cancer.^{4. Danforth’s Obstetrics & Gynecology, p. 644BC; 647FG; 10. Berek, p. 159D}  Be sure to discuss your symptoms with your health care professional.
  
  
• What if my period is irregular?
  Women with metrorrhagia or irregularly timed periods have inconsistent menstrual cycles.^{10. Berek, p. 159 A} Irregular periods are most common during the first few years of menses, and the years right before menopause.^{10. Berek, p. 159 D; 20. Treloar p. 124 C} Some women continue to have irregular periods throughout their childbearing years, which can be common due to age, but should be evaluated by a health care professional.^{18. Speroff, p. 549B; 10. Berek, p. 159 A} Oral contraception is one treatment option that can help regulate menstrual cycles.^{18. Speroff, p. 540; 39. Alesse PI p. 20}
  
  
• What if my period is too frequent?
  Some women have periods that occur more frequently than every 21 days. This is known as polymenorrhea.^{10. Berek, p. 159 A} Variations in menstrual cycles are most common during the few years right after menarche (first period) and in the years right before menopause. ^{20. Treloar p 124 C, 10. Berek p 159} Even though frequent periods can be common, women who have them should have a thorough medical history and physical exam conducted by a health care professional to rule out any other causes.^{18. Speroff, p. 555}
  
  
• What if my period is heavy or prolonged?
  Having regularly timed episodes of heavy or prolonged menstrual bleeding is called menorrhagia.^{10. Berek, p. 159 A} Women with a consistent menstrual flow for 7 or more days,^{18. Speroff, p. 549 B} or blood loss exceeding a little more than 5 tablespoons (>80 mL)^{34. Hallberg, p. 349-350} should be evaluated by a physician.^{18. Speroff, p. 549 B} Occasionally, heavy periods can indicate other health problems, and can also cause anemia.^{18. Speroff, p. 555} Talk to your health care professional if you experience heavy or prolonged bleeding so he or she can conduct tests to rule out more serious conditions.^{18. Speroff, p. 555} If the bleeding is not part of a more serious condition, oral contraceptives are one treatment option that can provide a beneficial impact on menstrual flow.^{Speroff, p. 540}
  
  
• What if my period is painful?
  Painful periods (also called dysmenorrhea) usually involve cramping in the lower abdomen or back.^{18. Speroff, p. 539} For some women, painful periods subside after their first pregnancy. ^{18. Speroff, p. 539} Oral contraceptives are one treatment option that can provide a beneficial impact on dysmenorrhea.^{18. Speroff, p. 540} Talk to your health care professional about what you can do to treat painful periods.
  
  
• Does bleeding every month guarantee that you're not pregnant?
  Not necessarily. The most common symptom of pregnancy is amenorrhea (the absence of menstruation). First trimester vaginal bleeding is very common, occurring in approximately 25% of patients who are known to be pregnant.^{6. Fleischer, p. 14; 640B; 644B} Other symptoms of pregnancy include nausea, enlargement of the breasts, and a growing abdomen.^{7. Dorland's Medical Dictionary, p. 1500} Contact your health care professional if pregnancy is suspected.
  
  
• What is a withdrawal bleed?
  When a woman is taking an oral contraceptive, her period is called a withdrawal bleed, because it happens during the time when she's taking placebo pills (inactive pills, without hormones).^{1. Pincus, p.1344A ; 2. Mishell, p. 904A; 39. Alesse PI, p. 21} The Pill was originally designed this way so that it would more closely mimic the experience of menstruation when not on the Pill.^{3. Loudon, p. 487C}
  
  
• What about extended-cycle contraceptives? Is it safe to skip periods by using an oral contraceptive?
  Recent surveys have questioned the necessity of monthly withdrawal bleeds.^{40. Sulak, Keuhl, p. 1142; 41. Sulak, Cressman, p. 179; 42. Nakajima, p. 32} Many health care professionals agree that it is not medically necessary for a woman to get her period. ^{43. Lybrel Study, p. 251, 262}
  
  

Health care professionals sometimes prescribe oral contraceptives to help regulate irregular periods or to help address other menstrual irregularities.^{18. Speroff, p. 540}

Talk to your health care professional if you have concerns about your monthly cycle or if you're experiencing symptoms that interrupt your life. Use the Annual Visit Checklist to help guide your conversation.