By Ellie Rodgers, Contributing Writer, myOptumHealth
Some women can trust their menstrual cycles to arrive each month like clockwork. They know how long their periods will last and how light or heavy they’ll be.
For other women, their periods are a guessing game. Will they be early, late or arrive at all? Will they last a day, or drag on for a week and a half?
Some irregularity may be normal. But it can also be a sign of a problem. Here’s how to tell the difference.
An average menstrual cycle – from the first day of one period to the first day of the next – is about 28 days. In adults, normal cycles are 21 to 35 days. In teens, the normal range is 21 to 45 days.
When a girl first starts her period, it can take up to two years for her cycle to become regular. She may miss periods or have two in one month, for example.
Cycles may begin to change as women age, sometimes starting as early as age 35. But women are usually closer to 50 when this change occurs.
As women get closer to menopause, irregular periods are common. They may skip periods or have very short cycles.
What could be a problem?
Pregnancy. If you miss a period or you have abnormal vaginal bleeding and are sexually active, you could be pregnant. See your doctor.
Periods too far apart or no periods. If you’re only having three or four periods a year (oligomenorrhea) or no periods (amenorrhea), the cause could be:
- Dieting, weight loss, an eating disorder, hormone problems, stress or too much exercise.
- Polycystic ovary syndrome (PCOS), a hormone imbalance. Other signs of PCOS include facial hair, weight problems and acne.
- Premature ovarian failure (POF), in which the ovaries stop working normally in women younger than 40. Symptoms may include hot flashes, night sweats and less interest in sex.
Periods too close together. If your periods are less than 21 days apart, it may be because of major life changes, hormone problems, stress or too much exercise.
Bleeding between periods or very heavy periods. Heavy bleeding or bleeding between periods may be caused by:
- Uterine fibroids. These are noncancerous tumors that may or may not need treatment.
- Cancer of the female reproductive organs.
- Endometriosis. This occurs when tissue that normally grows inside the uterus grows on the outside. Endometriosis can also cause pain and problems getting pregnant.
Talk to your doctor
If you are a girl or woman of childbearing age, see your doctor if:
- You haven’t started your period by age 15
- Your periods are very heavy (you soak through more than one tampon or pad every one to two hours)
- Your period lasts longer than seven days
- You have a period more often than every 21 days, or less often than every 45 days
- Your periods are 90 days or more apart
- You have severe pain
- You develop a sudden fever and feel sick after using tampons (if this happens, seek immediate medical attention)
If you are a woman nearing menopause, irregular periods are normal. But some types of bleeding are not. See your doctor if:
- You bleed very heavily with clots
- You bleed between periods or more often than every three weeks.
- You bleed after sex
- You bleed longer than what is normal for you
Also, see your doctor right away if you have already gone through menopause and you notice any bleeding from the vagina.
- Center for Young Women’s Health. Timing of my menstrual period. Accessed: 04/02/2008
- American College of Obstetricians and Gynecologists. Growing up. Accessed: 04/02/2008
- National Institute of Child Health and Human Development. Menstrual irregularities. Accessed: 04/02/2008
- The American College of Obstetricians and Gynecologists. Abnormal uterine bleeding. Accessed: 04/02/2008