Information about Hormonal Methods of Birth Control

Hormonal contraceptives are made up of female sex hormones: estrogen and progestin (a synthetic form of progesterone). The most popular hormonal contraceptive is the combination pill, or oral contraceptive (OC). Other hormonal contraceptions include injected progestins, subdermal implants that release progestins, transdermal patch, vaginal ring, and emergency contraception.

The Birth Control Pill

Four out of 5 women in the United States use oral contraceptives (commonly called "the pill") during their lifetime. The pill is the most popular form of reversible contraception (can be discontinued to restore fertility).

Recent studies have alleviated safety concerns about the pill. For most women, it is a safe form of birth control and provides several additional health benefits:

  • reduces the risk for ovarian and endometrial cancer
  • reduces bone loss associated with aging
  • regulates the menstrual cycle
  • relieves dysmenorrhea (pain associated with menstruation)
  • relieves perimenopausal (prior to the onset of menopause) symptoms
  • manages acne

If used correctly, women between the ages of 25 and 34 who take combination oral contraceptives with 0.05 mg of estrogen have a pregnancy rate of 0.25 percent in the first 1 or 2 years of use. That is, only 2.5 women out of 1000 become pregnant during the first year. The pregnancy rate is slightly higher when the level of estrogen is less than 0.05 mg per pill.

Some studies have shown that obesity/overweight can affect blood concentration levels of hormones and reduce the effectiveness of oral contraceptives. In women who are obese, it may take longer for hormone levels to reach the concentration necessary to prevent conception.

Side effects of hormonal birth control include the following:

  • increases risk for thromboembolism (blocked blood vessel) and stroke, especially in women who smoke
  • weight gain
  • irregular menstrual bleeding
  • increases blood pressure
  • adverse effects on cholesterol and lipid levels

There are several different oral contraceptives, allowing women more choices to select a product that best suits their needs.

YAZ® is a combination birth control pill approved by the Food and Drug Administration (FDA) that effectively prevents pregnancy; treats emotional and physical symptoms of premenstrual syndrome (PMS); and also can cause shorter, lighter, and more regular menstrual periods.

Quartette™ (levonorgestrel/ethinyl estradiol and ethinyl estradiol) is another type of oral birth control. In each 91-day course of this contraceptive, a tablet (light pink for the first 42 days, pink for the next 21 days, purple for the following 21 days, and yellow for 7 days) is taken at the same time each day, starting on the Sunday after the start of the menstrual period. Using this birth control method, women typically have about 4 menstrual periods per year instead of monthly periods (menstrual bleeding occurs when taking the yellow pills).

Quartette should not be used by women at risk for arterial or venous thrombotic diseases, including women over the age of 35 who smoke and those who have certain medical conditions (e.g., cerebrovascular disease, coronary artery disease, blood clots, uncontrolled high blood pressure, liver disease, history of breast cancer, etc.).

Injectable Hormones

The most common injectable hormonal contraceptive is Depo-Provera®, a synthetic hormonal substance also known as DMPA (depot-medroxyprogesterone acetate) that is injected into the muscle in the upper arm or buttocks every 3 months. Another, shorter-acting injectable hormone, norethdrone enanthate, is injected at a higher dose every 2 months. Injectable hormones prevent pregnancy by suppressing ovulation; by making it more difficult for the sperm to swim through the cervical mucus; and by destroying the endometrial lining of the uterus, keeping fertilized eggs from implanting.

DMPA is a safe and highly effective contraceptive. The success rate for women using DMPA is 99.7%. It reduces menstrual cramps, iron-deficiency anemia, and the risk for endometrial cancer. A disadvantage of DMPA is that it requires visits to the doctor or other health care professional every 3 months.

Side effects include:

  • Abdominal discomfort
  • Dizziness
  • Hair loss
  • Headaches
  • Irregular bleeding
  • Loss of bone density
  • Mood changes
  • Nervousness
  • Weakness or fatigue
  • Weight gain

About fifteen percent of women between 15 and 17 years of age use DMPA for birth control.

Subdermal Implants

Subdermal implants, also known as contraceptive implants, are matchstick-sized, hollow, rubber rods filled with synthetic progestin that are placed under the skin on the inside of the upper or lower arm. Subdermal implants were FDA-approved for use in the United States in 1991. Norplant® is the most commonly used brand.

The tubes provide a slow, constant release of progestin into the bloodstream, maintaining hormone levels. Possible side effects include irregular bleeding, changes in the menstrual cycle, weight gain, and breast tenderness.

Subdermal implants are the most effective method of birth control and one of the most cost-effective, but only 1.3 percent of women in the United States use this form. The implants are effective for up to 5 years and can be removed by a physician at any time. Inserting and removing them requires local anesthesia and a small incision. New capsules are being developed to make insertion and removal easier.

Transdermal Administration (Birth Control Patch)

The birth control patch is a form of hormonal contraception that delivers a steady level of the hormones norelgestromin/ethinyl estradiol (progestin and estrogen) into the bloodstream through the skin. Ortho Evra has been shown in clinical trials to be 99 percent effective in preventing pregnancy. The hormones in the patch prevent pregnancy by suppressing ovulation and by thickening the cervical mucus, making it difficult for sperm to enter the uterus. Each square patch is less than 2 inches in size and is thin enough to be unobtrusive under clothing.

The patch is worn directly on the skin and can be applied on the upper torso (back or front, but not on the breasts), abdomen, upper arm, or buttocks. It is changed once a week, on the same day of the week, and is worn for 3 weeks per month. A new patch must be applied immediately after removing the old one. It is worn continuously, including while exercising, showering, bathing, and swimming. If the patch loosens or becomes detached, backup contraception (e.g., diaphragm, condom) may be necessary and a health care professional should be consulted.

Side effects include the following:

  • Abdominal pain
  • Application site reaction
  • Breast tenderness
  • Menstrual cramps
  • Nausea
  • Upper respiratory infection

Rare, serious side effects include blood clots, stroke, or heart attack. Cigarette smoking increases the risk for developing serious side effects, especially in women over age 35.

The birth control patch was approved in November 2001 by the U.S. Food and Drug Administration (FDA) and is available by prescription. In January 2008, the FDA approved a label warning indicating that women who use the birth control patch are at higher risk for developing blood clots than women who use birth control pills.

Etonogestrel Ethinyl Estradiol Vaginal Ring

The vaginal ring (NuvaRing®) is a once-a-month form of hormonal contraception that delivers steady levels of the pregnancy-preventing hormones etonogestrel and ethinyl estradiol into the body. The ring is made of a flexible, transparent polymer and is approximately 2 inches in diameter and about one-eighth inch thick. The ring is self-inserted and does not require a visit to the doctor's office. In clinical trials, 1 or 2 out of every 100 women who use the vaginal ring as directed become pregnant.

The ring is inserted into the vagina, remains in place for 3 weeks, and is removed for the fourth week. Menstruation should begin a few days into week 4. A new ring is inserted 1 week after removing the old one, at about the same time of day. The ring must stay in place continuously to be effective. If it slips out, the same ring may be reinserted if fewer than 3 hours have elapsed. If more than 3 hours have elapsed without the ring in place, the ring can be reinserted, but backup contraception (e.g., condom) is necessary. When in place, the ring may interfere with diaphragm placement, so a diaphragm should not be used as backup contraception.

Common side effects include the following:

  • Headache
  • Nausea
  • Vaginal discharge
  • Vaginal infection
  • Weight gain

Rare, serious side effects include blood clots, stroke, heart attack, high blood pressure, and liver tumors. Cigarette smoking increases the risk for developing serious side effects, especially in women over age 35. A health care provider should be consulted for complete information regarding side effects of hormonal contraceptives. The vaginal ring does not provide protection from sexually transmitted diseases (STDs) and infections (STIs) or HIV.

NuvaRing® was approved by the U.S. Food and Drug Administration in October 2001 and is available by prescription.

Emergency Contraception

Emergency contraceptive pills (ECP) have been marketed in the United States within the past several years. ECPs must be taken within 72 hours of unprotected intercourse to be effective. ECPs do not disrupt pregnancy and are not considered abortifacients (something that induces or causes an abortion).

Emergency contraceptives include:

  • Plan B
  • Next Choice (levonorgestrel) and ella (ulipristal acetate)
  • Combination oral contraceptives

Plan B emergency contraceptive (e.g., Plan B One-Step, Plan B, Ella) is a high-dose oral contraceptive (two pills) that may reduce the risk for pregnancy by as much as 89 percent, if taken within 72 hours (3 days) of unprotected intercourse. It will not terminate an existing pregnancy.

In November 2012, the American Academy of Pediatrics issued a policy stating that doctors should let their teenage patients know about emergency contraception, such as Plan B, and write them a prescription for it if they are sexually active. According to researchers, having a prescription ready to go can make it more likely that teens will use emergency contraception to prevent unplanned pregnancy.

Prior to an April 2013 decision by the FDA, Plan B was available without a prescription for girls 17 and older and boys 18 and older, but younger teens need a prescription in most states. On April 30, 2013, the FDA announced the approval of Plan B One-Step emergency contraception without a prescription for women 15 years of age and older. According to the FDA, labeling for this product will be revised to: "not for sale to those under 15 years of age *proof of age required* not for sale where age cannot be verified."

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 01 Nov 2000

Last Modified: 26 Sep 2013