Menstrual Cycle & Periods

Quick look at the menstrual cycle and periods

A woman’s period, or menstruation, is when the lining of the womb sheds, along with blood, exiting through the vagina. When these periods occur regularly, this is referred to as the menstrual cycle.

A period happens if egg fertilization does not occur. This menstruation usually lasts 3-5 days. The average menstrual cycle lasts 28 days, but can range from 21-45 days depending on the woman’s age.

The cause of the monthly period is related to the changes a woman’s body undergoes in ovulating an egg roughly once a month for possible reproduction.

Various treatment options are available for the many women experiencing abnormal (heavy, irregular or painful) periods and other issues.

Why women have periods & what happens to her body

A woman’s period is related to the changes her body undergoes in ovulating an egg for possible fertilization. The period, or menstruation, is when she sheds the lining of the uterus and other blood after her ovulated egg is not fertilized. The uterine lining is no longer needed for an embryo to implant to for pregnancy. When the periods occur with regularity, this is called the menstrual cycle.

Women’s ovaries are in the lower part of the abdomen located on either side of the uterus. The ovaries start to produce hormones around puberty, which causes changes to the lining of the uterus (womb). The period, which is the shedding of the lining, is known as menstruation. For most women, the menstrual period occurs once a month and lasts from three to five days.

The menstrual cycle provides the hormones estrogen and progesterone, which rise and fall during the month to control the cycle. The average menstrual cycle lasts 28 days. But in adults it can range anywhere from 21 to 35 days, and in teens can range from 21 to 45 days.

Estrogen levels begin to rise in the first half of the cycle, which prompts the lining of the uterus to grow and thicken. This lining nourishes the embryo if a pregnancy occurs. During this same time frame, an egg in one of the ovaries begins to mature.

About half way through the menstrual cycle ovulation takes place. Ovulation is when the egg leaves the ovary. The egg will then begin traveling through the fallopian tube toward the uterus. During this time, hormone levels continue to rise and help prepare the wall of the uterus for pregnancy. Women are most likely to get pregnant during the three days prior to, or on the day of ovulation.

Pregnancy occurs if the egg is fertilized by a man’s sperm and the resulting embryo attaches to the uterine wall. If the egg is not fertilized, hormone levels drop, which signals for the next menstrual cycle to begin and the egg will be shed with the uterine lining in the next period.

Is my period normal?

Everyone’s period is different. The amount of blood, called the menstrual flow, could be light, moderate or heavy. The length of the period also varies in women, with most periods lasting between three and five days. As a woman matures, her cycle tends to shorten and become more regular.

In the United States, the average age a girl starts her period is 12, but it can start as early as 8 or as late as 15. The first period tends to start about two years after a girl’s breasts begin to develop. If a girl has not started her period by age 15 or two to three years since breast growth started, she should make an appointment with her healthcare provider.

A woman usually has her periods until menopause, which occurs between the ages of 45 and 55. During menopause a woman stops ovulating (releasing eggs) and can no longer get pregnant.

Problems with periods

The menstrual cycle and a woman’s period can have a range of problems including, pain, irregularity and heavy bleeding. Some common problems women experience with their periods follow.


Lack of a menstrual period. Amenorrhea describes the absence of a period in young women who have not started their period by age 15, or in women who have not had their period for 90 days. This can be caused by eating disorders, excessive exercising, stress or a medical condition. If at any point a woman does not have her period for 90 days, she should see her doctor to check for pregnancy, early menopause or other possible health problems.


Painful periods, including severe cramps. Most teens with dysmenorrhea do not have a serious disease, rather their body is producing too much of a chemical called prostaglandin that causes menstrual cramps. In older women this pain can be caused by various conditions such as endometriosis or uterine fibroids. Women who experience painful periods should speak to their OB-GYN about their symptoms.

Abnormal uterine bleeding (AUB)

Bleeding that is irregular for a woman’s normal menstrual period. AUB can include:

  • Bleeding between periods
  • Bleeding for more days than normal
  • Bleeding after sex
  • Bleeding after menopause
  • Heavy bleeding
  • Spotting anytime in the menstrual cycle.

Abnormal bleeding can be caused by many different issues. When experiencing AUB, it is important for women to see their doctor to begin checking for causes. Some causes are not serious and are easy to treat, but others could be more serious.

Heavy or prolonged bleeding

One of the most common forms of AUB. A woman’s period is considered heavy if there is enough blood to soak a tampon or pad every hour for several consecutive hours. Other symptoms can include passing blood clots larger than a quarter during menstruation, needing to change pads or tampons during the night, or a period that lasts longer than seven days.

If a woman experiences heavy menstrual bleeding, it is important that she see an OB-GYN. Evaluation for irregular, painful or heavy periods might include:

  • Consultation with an OB-GYN to discuss symptoms
  • Pelvic ultrasound to evaluate for structural problems with the uterus
  • Blood tests.

Examples of treatment options for irregular, painful and heavy periods

Hormone therapy

Hormone therapy is often an initial option for treating period issues. Hormones found in birth control pills or IUDs (intrauterine devices) stabilize the lining of the uterus, regulate menstrual cycles or correct hormonal imbalances. They can also reduce pelvic pain, cramping or other symptoms accompanying the menstrual cycle.


Nonsteroidal anti-inflammatory medications (Advil, Motrin, Aleve, ibuprofen) minimize production of prostaglandins, the chemical that causes cramps.

Lysteda (tranexamic acid) is a nonhormonal medication that promotes blood clotting and may be recommended for women experiencing heavy bleeding.


Surgery is recommended when anatomical problems lead to irregular periods, particularly in women who want to have children. It may also be done to remove severe scar tissue (adhesions) in the reproductive tract. In more severe cases, surgery may be used to remove a woman’s uterus to eliminate periods altogether.

Surgeries for period problems may include:

  • D&C (dilation and curettage) – a brief surgical procedure that dilates the cervix and scrapes the lining of the uterus.
  • Hysteroscopy – a minimally invasive procedure that uses a hysteroscope to allow the doctor to see inside the uterus and remove masses from its cavity.
  • Endometrial ablation – a procedure destroying the endometrium (lining of the uterus) to lighten or stop a woman’s period. It is not recommended for women who wish to become pregnant in the future.
  • Hysterectomy – the surgical removal of the uterus and cervix.