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Birth Control Pills; Overview.

More than 45 years since the U.S. Food and Drug Administration (FDA) approved "the pill" in 1960, it continues to be the most popular and one of the most effective forms of reversible birth control ever invented. According to the Johns Hopkins School of Public Health Population Information Program, more than 18 million US women rely on birth control pills, also called oral contraceptives, as their birth control method. Today, American women have more than 40 different oral contraceptive products from which to choose.

Unlike the original oral contraceptives used decades ago, low-dose forms with few health risks are the norm. Today's birth control pills (BCPs) even offer health benefits.

Despite the fact that they are safe for most women, however, BCPs do carry some health risks. For example, if you are over 35 and smoke or have certain medical conditions such as a history of blood clots or breast or endometrial cancer, your health care professional may advise against taking BCPs. Also, birth control pills do not protect you from sexually transmitted infections (STIs), including HIV (human immunodeficiency virus), the virus that causes AIDS.

In recent years, birth control pills have been changed to include less hormones, resulting in fewer side effects. In fact, all healthy women who don't smoke may use birth control pills, regardless of their age.

Unlike other forms of birth control sold over-the-counter, you need a health care professional's prescription to purchase BCPs and many health insurers cover their cost. The one exception is the emergency birth control pill Plan B, which was just approved for over-the-counter sale by the FDA. Plan B is expected to be available over the counter by the end of 2006.

How Birth Control Pills Work

At the beginning of each menstrual cycle, estrogen levels begin to rise. Estrogen helps thicken the lining of the uterus (endometrium) to prepare for a fertilized egg. Once estrogen levels peak, about 14 days into the menstrual cycle, one of the ovaries releases an egg. This monthly release of an egg is called ovulation.

After ovulation, progesterone, another reproductive hormone, begins to rise. Over the next seven days, progesterone further prepares the endometrium for a fertilized egg. Conception occurs when a fertilized egg implants itself in the uterine lining.

If conception does not occur, both estrogen and progesterone levels drop, signaling the now thickened uterine lining to slough off or shed, and menstruation begins.

Birth control pills are a synthetic form of the hormones progesterone and estrogen. They prevent ovulation by maintaining more consistent hormone levels. Without a peak in estrogen, then, the ovary doesn't get the signal to release an egg. No egg means no possibility for fertilization and pregnancy. They also thicken cervical mucus so the sperm cannot reach the egg, and make the lining of the uterus unreceptive to the implantation of a fertilized egg.

Types of Birth Control Pills

The three most common types of birth control pills are:

1. Progestin-only pills (POP). This type of pill contains no estrogen. Called the progestin-only pill, or "mini-pill," it's ideal for breastfeeding women because estrogen reduces milk production. It's also ideal for women who cannot take estrogen. Progestin-only pills primarily work by thickening the cervical mucus, thereby preventing sperm from entering the uterus. To work effectively, they must be taken at a certain time every 24 hours.

Advantage of POPs:

decreased menstrual blood loss

decreased menstrual cramps and pain

can be used by breast-feeding women immediately after delivery

an option for women who cannot use estrogen, such as those who are over 35 and still smoke

easily reversible


irregular bleeding patterns, spotting or breakthrough bleeding

must be taken at the same time every day

do not protect against sexually transmitted infections; women at risk must use condoms

may be slightly less effective than combination oral contraceptives

Possible side effects:

amenorrhea (absence of a monthly period)

irregular bleeding

heavy bleeding

abdominal pain


Ask yourself the following questions to determine if POPs are the right choice for you:

Are you the type of person who can remember to take a pill at exactly the same time every day?

Will irregular bleeding or spotting bother you or interfere with intimacy?

Are you breastfeeding, but feel that you need contraception?

If you are at risk for sexually transmitted infections, will you use condoms for protection?

Do you need to avoid taking estrogen?

2. Combination pills. When you hear the term "birth control pill," it most often refers to oral contraceptives containing estrogen and progestin. Each pill in the pack contains a combination of these two hormones.

Monophasic pills. Each of the 21 active pills in one of these packs contains the same amount of estrogen and progestin. The other seven pills are placebos and contain no hormones; menstruation occurs while they are being taken. In September 2003, the Food and Drug Administration (FDA) approved a 91-day oral contraceptive regimen called Seasonale, in which you take a pill containing progestin and estrogen for 12 weeks (84 days), followed by one week of placebo tablets. If you use this product, you only menstruate about once every three months instead of once a month.

Multiphasic pills. Also called biphasic and triphasic, multiphasic oral contraceptives contain varied amounts of hormones and are designed to be taken at specific times throughout the entire pill-taking schedule. Multiphasic pills contain various levels of estrogen and progestin throughout the month. They were developed to reduce side effects of oral contraceptives, including breakthrough bleeding, spotting and amenorrhea, associated with higher levels of hormones.

Continuous use pill. In May 2007, the FDA approved Lybrel, first continuous use birth control pill. It is a multiphasic pill that comes in a 28-day pack and is designed to be taken continuously, with no break in between pill packets. That means you won't have a period. However, you may have some spotting or breakthrough bleeding, particularly when you first start using Lybrel.

Advantages of combination pills:

reduces risk of ovarian cancer and endometrial cancer

prevents ectopic pregnancy (pregnancies that occur outside the uterus, usually in the fallopian tube)

decreases menstrual blood loss and pain and cramps

less severe premenstrual symptoms

more regular menstrual cycles

improves acne

prevents bone density loss in women who have attained their peak bone mass (generally women over 30)

less risk of ovarian cysts

improves excessive body hair, particularly on the face, a condition called hirsutism

improves endometriosis

improves symptoms of rheumatoid arthritis

beneficial effects on cholesterol (HDL and LDL)

decreases benign breast disease or breast cysts

reversible with quick return to fertility

treats the emotional and physical symptoms of premenstrual dysphoric disorder (PMDD), a severe form of PMS. Only one combination OC has been shown to be clinically effective for this use. It contains the progestin drospirenone and ethinyl estradiol, a form of estrogen.


could cause nausea, vomiting, headaches and/or spotting, particularly with the first few cycles

may lead to hypertension (less than one in 200 women)

may causes blood clots in a small percentage of users

may contribute to the formation of gallstones and rare benign liver tumors

Possible side effects:

nausea and vomiting


irregular bleeding

weight gain or weight loss due to changes in eating habits

breast tenderness

increased breast size

Ask yourself the following questions to determine if combined birth control pills are a good option for you:

Are you the type of person who can remember to take a pill every day?

If you are at risk for sexually transmitted infections, will you use condoms?

Do you need relief from endometriosis, severe menstrual pain or anemia?

If you still smoke, are you under 35?

If breastfeeding, is your baby six months or older?

Do you have high blood pressure?

Have you done well with combination pills in the past?

3. Emergency contraceptive pills (ECP). ECPs are not intended to be used regularly as a contraceptive. They are designed to prevent pregnancy after unprotected sex (when standard contraceptives fail or no method was used). The FDA has approved one emergency contraception pill called Plan B, which contains the progestin levonorgestrel. And women over 18 will soon be able to buy Plan B without a prescription--probably by the end of 2006--due to recent OTC approval by the FDA. Plan B will be available behind pharmacy counters to ensure that women who purchase it are 18 or over. In addition, certain regular oral contraceptive pill packs can be used for emergency contraception if you take several pills at the same time (the exact quantity depends on the brand), with guidance from your health care professional.

While the Plan B label calls for a two-dose regimen, with the first dose taken within 72 hours of unprotected sex and the second 12 hours later, studies find that both pills can be taken at the same time, and that Plan B is effective up to 120 hours after unprotected intercourse.

To learn more about how ECPs work and how to get them, ask your health care professional or pharmacist. Or visit the Internet site for emergency contraception operated by Association of Reproductive Health Professionals and the Office of Population Research at Princeton University ( or Emergency contraception used to be available by prescription only, although the FDA has just approved Plan B without a prescription, which is expected to be available over the counter by the end of 2006.

Advantages of ECP:

reduces the chance of unintended pregnancy

can be obtained easily--Plan B will soon be available over the counter for women 18 and over

can be obtained in advance and kept handy in case of an emergency such as condom breakage, missed oral contraceptives, late contraceptive injections or forced sex


timing, because you must take the first dose within 120 hour of having unprotected sex. The sooner you take them after unprotected intercourse, the more effective they are. That's why it's a good idea to have a prescription or a supply of emergency contraceptive pills available should the need arise.

Possible side effects:

nausea, vomiting, dizziness, fatigue and headache

an earlier next period, or, in rare instances, a later next period

heavier or lighter menstrual bleeding

breast tenderness

abdominal pain

Ask yourself the following questions to determine if you should have ECPs on hand or know where to find them:

Have you ever made love unexpectedly?

Have you ever been forced to have sex?

Has a partner had a condom break, slip or come off?

Have you ever forgotten to take several birth control pills?

Have you expected your partner to pull out before ejaculation, but he didn't?

Has your diaphragm slipped?

Have you been late for your Depo-provera or Lunelle shot and had unprotected sex?

Health benefits, risks and other medical issues about birth control pills

Birth control pills provide certain health benefits in addition to preventing pregnancy. Before you start taking oral contraceptives, discuss the health benefits and risks associated with them with a health care professional. Like any other medication, birth control pills can also cause side effects; they may interact with other medications you may take; or they may not be a good choice for you because of your personal health history. Benefits and risks associated with birth control pills are listed below:


Prevent pregnancy. First and foremost, birth control pills are one of the most effective forms of reversible birth control. If used correctly, the odds are that only five in 1,000 women is likely to get pregnant in the first year of use.

Improve your menstrual cycle. Birth control pills can improve your menstrual cycle in at least for ways, including:

less bleeding during periods; one product is designed to eliminate your periods entirely

more regular and consistent menstrual cycle patterns

relief from pelvic pain during menstruation

relief from primarily mood-related symptoms of premenstrual dysphoric disorder (PMDD), a condition that causes many of the same symptoms as PMS, but with more intensity. A combination oral contraceptive containing drospirenone, a progestin, and ethinyl estradiol, a form of estrogen, was recently approved by the FDA. Known as "YAZ," this OC was shown to be clinically effective both for the prevention of pregnancy and for the emotional and physical symptoms of PMDD.

Prevent cancer. Birth control pills have been shown to protect women from ovarian and uterine cancer, and possibly from colorectal cancer.

Improve bone density. Some studies have shown that it's possible that bone density improves while taking birth control pills. However, it has not been shown that BCPs make a difference in reducing bone fractures.

Protect you from ovarian cysts. If you take BCPs, you may have about one-fifth less risk for developing ovarian cysts than women using nonhormonal methods of contraception, such as diaphragms or condoms. Women using low-dose pills (20 mcg of estrogen) or multiphasic pills may not get the same benefit.


Heart attack. The chances of BCPs contributing to a heart attack are small (less than three additional heart attacks per million American women per year) unless you smoke. Studies have shown that smoking dramatically increases the risk of heart attack in women age 35 years or older, which is why BCPs are generally not prescribed to women in this age group who smoke. The American College of Obstetricians and Gynecologists (ACOG) notes that POPs may be appropriate for women with coronary artery disease, congestive heart failure or cerebrovascular disease. However, combined pills are not recommended for these women.

Ischemic stroke. There is a small, but significant increase in ischemic stroke risk when using birth control pills. This was a particular concern with early oral contraceptives that contained higher doses of estrogen, but newer preparations containing less estrogen are associated with a lower risk of stroke. In otherwise healthy young women (non-smokers without persistent high blood pressure), the risk is low.

Migraines and stroke. Women who take oral contraceptive and have a history of migraines have an increased risk of stroke compared to nonusers with a history of migraine. Your risk is greatest if you have migraines with "aura"--neurologic symptoms related to vision, such as blurred vision, temporary loss of vision or seeing flashing lights or zigzag lines. As a result, both the American College of Obstetricians and Gynecologists (ACOG) and the World Health Organization (WHO) have concluded that for women over age 35 who get migraines, the risks of BCPs use usually outweigh the benefits.

Venous thromboembolism (VTE). This rare condition causes clots to form in your blood vessels and can cause symptoms including pain, swelling, and varicose veins, and may block the flow of blood. The risk may vary with the type of progestin used in the pill.

Worsen severe diabetes. The estrogen in birth control pills may increase glucose levels while decreasing the body's insulin response, while the progestin in the pills may encourage overproduction of insulin. Use of birth control pills by diabetic women should be limited to those who do not smoke, are younger than 35 and are otherwise healthy with no evidence of persistent high blood pressure, kidney disease, vision problems or other vascular disease.

Possible acceleration of gallbladder disease. Estrogen may cause bile to become oversaturated with cholesterol, which can lead to gallstones.

No decreased risk of sexually transmitted infections. Birth control pills do not protect against sexually transmitted infections (STIs). But women who use birth control pills are less likely to develop symptomatic pelvic inflammatory disease (PID), which is an infection of the uterus, fallopian tubes or other reproductive organs. PID is a complication of STIs, especially chlamydia or gonorrhea, and may make you to infertile or cause chronic pain. If you are at risk for contracting an STI, you should consider also using condoms.

Lupus/sickle cell anemia. The American College of Obstetricians and Gynecologists notes that birth control injections or implants are safer alternatives than birth control pills in women with these health conditions.

Possible drug interactions

Some drugs can reduce the effectiveness of oral contraceptives. Likewise, oral contraceptives can interfere with the effects of some drugs.

These include:

Seizure medications: phenytoin, carbamazepine, primidone, ethosuximide, methylphenobarbital, paramethadione, phenobarbital, topiramate

Tuberculosis medication rifampin

Antifungal drug griseofulvin

Anti-anxiety drugs containing benzodiazepine


Bronchodilators such as theophylline

St. John's wort

If you take any medication either on a short- or long-term basis, be sure to ask your health care professional or pharmacist about possible interactions with birth control pills, and how you should avoid or manage them.

For example, you may need to use an additional contraceptive (such as condoms) as a backup contraceptive method, or take a higher or lower-dose pill formulation.


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Keywords: birth control pills, birth control, women, oral contraceptives, progestin-only pills, estrogen and progestin, side effects, possible side effects, emergency contraception, failure rates, combination pills, sexually transmitted infections, sexually transmitted diseases, hypertension, diabetic women, risk of breast cancer, risk for breast cancer, bone density, ovarian cysts, heart attack, ovarian cancer, endometrial cancer, cervical cancer, colorectal cancer
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Publication:NWHRC Health Center - Birth Control Pills
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Date:May 29, 2007
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