Oral Contraception

Oral contraceptives (OCs) are available only by prescription and come in either a combination of estrogen and progestin or progestin alone. Many brands of each form are available. Although both are equally effective with typical use, the combined pill is more effective with perfect use, and most women choose this form.

Some women, however, experience severe headaches or high blood pressure from the estrogen in the combined pill and must take the progestin-only pill. Not all combined pills or progestin-only pills are alike, and brands differ in the amount of estrogen or progestin they contain. Many OC combined brands now use lower estrogen doses than previous brands and are proving to be safe and effective while providing a better quality of life than earlier OCs.

For all OC users, a check-up at least once a year is essential. It is also important for women to have their blood pressure checked 3 months after beginning the pill. Former pill users who want to bear children usually regain fertility in 3 - 6 months, but they may regain it even sooner.

Hormones Used in Contraceptives
Estrogen (Estradiol)

Estrogen is the major female hormone and is responsible for female characteristics. The estrogen compound used in most oral contraceptives is estradiol and is always used with a progestin.

Effects on Reproduction. When used throughout a menstrual cycle with progesterone, it suppresses the actions of other reproductive hormones (luteinizing hormone, or LH, and follicle stimulating hormone, or FSH) and prevents ovulation. Estrogen also changes the cellular structure of the lining of the uterus (the endometrium) and hinders implantation of a fertilized egg.

Side Effects of Estrogen. During the first 2 - 3 months of use of oral contraceptives, side effects from estrogen in the combined pill include:

Nausea and vomiting (can often be controlled by taking the pill during a meal or at bedtime)
Headaches (in women with a history of migraines, they may worsen)
Dizziness
Breast tenderness and enlargement
Progesterone (Progestin)

When used in contraception, progesterone is referred to by one of several names:

Progesterone is the name for the natural hormone
Progestogen is a synthetic form
Progestin is the term for any hormone, natural or synthetic, that causes progesterone effects; it is used as the general term in this report
Progestins may be used alone or with estrogen in oral contraceptives. In addition, certain specific progestins are used in other kinds of contraceptives, such as etonogestrel in the Implanon implant and depo-medroxyprogesterone acetate in the injected Depo-Provera.

Progesterone can prevent pregnancy by itself in several ways:

It blocks luteinizing hormone (LH), one of the reproductive hormones important in ovulation.

It maintains a powerful barrier against the entry of sperm into the uterus by keeping the cervical mucus thick and sticky.
It reduces the mobility of the fallopian tubes, thereby inhibiting sperm transport.
It changes the lining of the uterus and makes it more difficult for the fertilized egg to implant.
Progestins used in contraceptives are referred to as:

Second generation (levonorgestrel, norethisterone).
Third generation (desogestrel, gestodene, norgestimate, drospirenone). The third-generation progestins tend to have fewer male-like side effects. Some studies suggest, however, they may pose a higher risk for blood clots than the older progestins, although the risk is still small.

Side Effects of Progestins. Side effects of progestin occur in both the combination oral contraceptives and any contraceptive that only uses progestin, although they may be less or more severe depending on the form and dosage of the contraceptive. Side effects may include:

Changes in uterine bleeding such as higher amounts during periods, spotting and bleeding between periods (called break-through bleeding), or absence of periods
Unexpected flow of breast milk (check with your doctor if this occurs to be sure other abnormalities are not causing it)
Abdominal pain or cramps
Diarrhea
Fatigue, unusual tiredness, weakness
Hot flashes
Decreased sex drive
Nausea
Trouble sleeping
Acne or skin rash (not all OCs have this side effect; low-dose OCs actually improve acne)

Depression, irritability, or other mood changes (although some OCs are helpful for women with premenstrual dysphoric syndrome)
Swelling in the face, ankles, or feet

Weight gain (however, combination oral contraceptives -- which contain progestins -- do not cause weight gain)

Newer formulations of combination pills that use low-dose estrogen, and newer progestins may reduce and even avoid many of these side effects, including weight gain. Low-dose progestins used in non-oral contraceptives, such as the LNG-IUS IUD, also may not pose as high a risk for these side effects. If side effects persist or are severe, a woman should always talk to her doctor. Many women do not experience these side effects, or for many of those who do, their bodies eventually adjust.


Combination Estrogen-Progestin Contraceptive Pills
Oral contraceptives that contain both estrogen and progestin are the more common type of OC. At least 10 million American women and 100 million women worldwide use combination OCs. When they were first marketed in the early 1960s, OCs contained as much as 5 times the amount of estrogen and up to 10 times the amount of progestins currently used. After reports of severe complications (stroke, heart attack, and pulmonary embolisms) in young women, the hormone amounts were significantly reduced.

The estrogen compound used in most oral contraceptives is ethinyl estradiol (also called estradiol or EE). Fifty micrograms of estradiol is considered to be high dose, 30 - 35 micrograms are considered average dose, and 20 micrograms or less is low-dose. (The high doses found in current OCs are still much lower than earlier forms of the pill.) Experts recommend using the lowest possible progestin and estrogen doses. Estrogen doses should not exceed 50 micrograms as higher doses increase the risk for complications.

Many different types of progestins are used in combination with estradiol. Some common types of progestin, and popular combination oral contraceptive brands, include:

Desogestrel is the progestrin used in Mircette. Approved in 1998, Mircette was the first oral contraceptive to offer a low estrogen dose and a new type of dosing regimen.

Drospirenone is used in Yasmin and Yaz. (Yaz contains a lower dose of estrogen than Yasmin.) Because drospirenone increases blood levels of potassium, women should not use Yasmin or Yaz if they have kidney, liver, or adrenal diseases.
Levonorgestrel is used in Seasonale and Seasonique, as well as many other oral and non-oral contraceptives.

Norethindrone is used in Loestrin and Loestrin 24 Fe (which adds iron supplements to the placebo pills).

Norgestrel is used in various generic and brand contraceptives.
Many types of medications and supplements (Tylenol, anti-seizure drugs, antibiotics, vitamin C, St. John’s wort) can interact with progestin and reduce its effectiveness. Make sure your doctor is aware of any drugs, vitamins, and herbal supplements that you take.

Types of Regimens. Combination pills are sold in 21-day or 28-day packs:

Each pill in a 21-day pack contains estrogen and progestin. Women take 1 pill a day for 21 days, and then wait 7 days before starting a new 21-day pack.
28-day packs typically start with 21 hormone pills and add 7 placebo pills that do not contain hormones. After taking hormone pills for 21 days, a woman takes the inactive pills for 7 days. Some newer brands, like Yaz, use 24 days of active pills and 4 days of inactive pills. Mircette uses 21 days of low-dose progestin and estrogen, followed by 2 placebo days, and then 5 days of very low-dose estrogen. Loestrin 24 Fe uses 24 days of active pills followed by 4 days of iron-containing placebo pills.

OCs may be taken in cycles that include pills of the same or different strengths. These are categorized as monophasic (one-phase), biphasic (two-phase), or triphasic (three-phase). Monophasic pills contain the same amount of hormones in each dose. Biphasic and triphasic pills contain different dosages of hormones within the pill packs. Because monophasic pills have a consistent amount of hormones, they tend to cause fewer hormone-fluctuating side effects than biphasic or triphasic pills. Several 2006 reviews found little difference in effectiveness between these three types of oral contraceptives. Many experts recommend monophasic pills as the best first-choice for birth control pills.

Continuous-Dosing Oral Contraceptives. With standard birth control pills, a woman gets her period a few days after completing the active pills in her pack. Continuous dosing, (also called extended use), oral contraceptives aim to reduce -- or even eliminate -- monthly periods. Seasonale, the first continuous use oral contraceptive, was approved in 2003. It contains 84 days of active pills followed by 7 days of inactive pills. Seasonale produces a period about once every 3 months.

In 2006, the FDA approved Seasonique, a follow-up to Seasonale. Seasonique is also a 91-day pill cycle, but it includes 84 days of pills that contain levonorgestrel and estradiol, and 7 days of pills that contain only low-dose estradiol. As with Seasonale, women who take Seasonique have about 4 periods a year. The FDA is also reviewing Lybrel, which supplies a low-dose of hormones for 365 days a year. In clinical trials of Lybrel, some women stopped having periods altogether.

Taking the Pills. A woman usually takes the first pill either on the Sunday after her period starts or during the first 24 hours of her period. (The first pill can be started at any time during the menstrual cycle without affecting the bleeding patterns. Ovulation can occur that month, however.) The remaining pills are taken once a day, ideally at the same time of day, until the pack is used up. If a woman has a 21-day pack, she waits 7 days before starting a new pack. If she is on the 28-day pack, she takes the 7 inactive pills.

If you skip one or more pills, take the following precautions:

Missing the first pill in a new cycle. Take a tablet as soon as you remember and the next one at the usual time. Two tablets can be taken in one day. Use barrier contraception for 7 days after the missed dose. [See Spermicidal and Barrier Contraception.]

Missing a pill 2 days in a row. Take 2 pills as soon as you remember and then 2 more the following day. Also use back-up barrier contraception until the next pill cycle.
Missing more than 2 days. Discard the pack, use a back-up birth control method and begin a new cycle on the following Sunday, even if you have started bleeding. One study found that women who miss 3 pills will probably still not ovulate, but nevertheless, they should take all necessary precautions to prevent pregnancy.
Progestin-Only Oral Contraceptives ("Mini-Pills")
Progestin-only pill brands include:

Levonorgestrel (Plan B)
Norethindrone (Micronor, Avgestin, Norlutin, Nor-QD). (This progestin is made from male hormones, so may cause more male side effects than others.)
Norgestrel (Ovrette)

Progestin-only pills, which only contain progestins, are always sold in 28-day packs and all the pills are active. (An exception is Plan B, which is emergency contraception.) Progestin-only pills must be taken at precisely the same time each day to maintain top effectiveness. If a woman deviates from her pill schedule by even 3 hours, she should call her doctor about using back-up contraception for the next 2 days. Progestin-only pill users will experience even lighter periods than those taking combination pills. Some may not have periods at all. These hormones should not be used by premenopausal women in their 40s, since they pose a higher risk for adverse effects in this group.

Advantages of Oral Contraceptives
Oral contraceptives are the choice of most American women who use birth control, making them the most popular reversible contraceptives in the U.S. OCs are among the most effective contraceptives. Failure rates are very low and are usually due to noncompliance. Some studies have suggested that women who are overweight may have a higher risk for failure. The risk for these women is also still very low, however.

OCs also have the following advantages:

More sexual freedom. OCs do not interfere with intercourse, and in fact, many women report that sex is more pleasurable because they no longer have to worry about pregnancy.

Reduce menorrhagia (heavy bleeding) and, therefore, reduce the risk for anemia.
Reduction in dysmenorrhea (severe pain). High-dose OCs have been especially helpful, but they carry risks. Specific newer low-dose OCs that contain certain progestins, such as Yasmin (with drospirenone) and Mircette (with desogestrel), may reduce menstrual pain.

Possible reduction in premenstrual syndrome with specific OCs, notably Yaz (which was approved for treating premenstrual dysphoric disorder -- premenstrual depression -- in 2006.) Some OCs, however, are associated with worse emotional changes. Monophasic OCs may have a more beneficial effect on mood than triphasic OCs.


Reduction in endometriosis.
Endometriosis is the condition in which the tissue that normally lines the uterus (endometrium) grows on other areas of the body causing pain and irregular bleeding.
Reduction of ovarian cancer. OCs may reduce the risk of ovarian cancer by 30 - 50% (even in women with genetic risk factors). Progestin appears to be the protective factor by suppressing ovulation. Protection occurs after 5 years of use and persists for 10 - 20 years after stopping. Some experts believe that women at particular risk for ovarian cancer might consider oral contraceptives with the highest progestin dose.

Reduction of endometrial (uterine) cancer. According to some studies, older OCs reduced the risk for endometrial cancer by half. More studies are needed on newer formulations, which have lower doses of estrogen, but it is generally believed that they, too, are protective.

Possible protection against colon cancer. Duration of use does not seem to be associated with decreased risk, but protection appears stronger for women who have used oral contraceptives more recently.

Possible protection against multiple sclerosis. Some studies have suggested that women who take oral contraceptives may be less likely to develop multiple sclerosis
Acne improvement with low-dose OCs. (Some low-dose OCs, such as Ortho Tri-Cyclen, have been specifically approved for acne reduction, although most low-dose OCs reduce testosterone levels and so help reduce acne.)
Possible protection against bone loss with low-dose OCs. The effect of OCs on bone density is unclear and may depend on the specific formulas and types of progestins used.

Disadvantages and Complications of Oral Contraceptives
Common Side Effects. Estrogen and progesterone have different side effects. Women on the combined pill may experience different effects from those on the progestin-only pill. Symptoms of serious problems include severe abdominal pain, chest pain, unusual headaches, visual disturbances, or severe pain or swelling in the legs. In spite of some concerns, combination OCs do not generally cause weight gain.

[For specific side effects of estrogen and progestin, See Box Hormones Used in Contraception.]

Serious Effects on Heart and Circulation. Combination birth control pills contain estrogen, which can increase the risk for stroke, heart attack, and blood clots in some women. The risk is highest for women who smoke or have a history of heart disease risk factors (such as high blood pressure) or cardiac events. Women who have certain metabolic disorders, such as polycystic ovary syndrome (PCOS), are also at higher risk for heart-related complications associated with these pills.

When birth control pills were first introduced, heart and circulatory risks were higher than they are now. Current brands of combination oral contraceptives contain much lower dosages of estrogen and are safer than those earlier pills. However, a 2005 review suggested that even low-dose combination birth control pills have some cardiovascular risks. Women should discuss their lifestyle and health history with their doctors to decide if birth control pills are a safe option. For women with heart disease risk factors, progestin-only (“mini-pill”) oral contraceptives may be safer than combination estrogen-progestin oral contraceptives.


Breast Cancer. Studies have been conflicting about whether estrogen in oral contraception increases the chances for breast cancer, and if it does, which women are at risk. Some research supported a higher risk in women with a family history of breast cancer and who also used OCs before 1975, which contained high-dose estrogens and progestins. A reassuring 2002 study supported an earlier major study, with both finding no evidence that current OC use increases the risk for breast cancer. It also reported no higher risk in women who had taken OCs for 15 years of more or had taken them at young ages. Some issues remain unresolved. For example, the risk for women currently taking OCs around menopause (ages 45 - 64) is still unclear. OCs users with a family history of breast cancer or who carry the BRCA1 genetic mutation (although possibly not those with the BRCA2) may be at higher risk. Such women are at higher risk for breast cancer in any case.

Cervical Cancer. Numerous studies report a strong association between cervical cancer and long-term use of oral contraception (OC). The risk is highest (up to four times the risk of nonusers) in women infected with human papillomavirus (HPV) who have taken OCs for 10 years or more. (Women who are not infected with HPV have no significantly higher risk.) The reasons for this risk from OC use are not entirely clear. Some experts have suggested that the hormones in OCs might facilitate entry of the HPV virus into the genetic material of cervical cells. Certainly, women who use OCs are less likely to use a diaphragm, condoms, or other methods that offer some protection against sexually transmitted diseases, including HPV.


Other Complications. Other complications have been associated with the use of oral contraceptives:

Taking oral contraceptives containing certain progestins (desogestrel in one study) may increase the risk for periodontal disease. Other types of progestins do not pose a risk for gum disease.
There has been some debate over whether the progestin-only pill increases the risk for permanent type 2 diabetes in women who develop a temporary form of diabetes during pregnancy (called gestational diabetes). In any case, the low-dose combination pill does not appear to pose such a risk. Women with a history of gestational diabetes should discuss this controversy with their doctor.
Some evidence suggests that oral contraceptives may reduce lung capacity during exercise. In fact, there have been a few reports of worsening of asthma with OCs, but this is an uncommon effect.
The pill can affect the liver and, in rare cases, has been associated with liver tumors, gallstones, or jaundice. Women with a history of liver disease, such as hepatitis, should consider other contraceptive options.
Interactions with Other Medications. Oral contraceptives can interact with many other medications and herbal supplements.

Other Methods for Administering Combination Hormones
New methods of administering the combination of progestin and estrogen are now available. Failure rates with perfect use (0.1 - 0.6%) are similar to those with combined oral contraceptives. The recommendations and side effects are the same as those for OCs. None of these methods protect against sexually transmitted diseases.

Skin Patches. Ortho Evra was approved in 2002 as the first birth control skin patch. It contains a progestin (norelgestromin) and estrogen. The patch is placed on the lower abdomen, buttocks, or upper body (but not on the breasts). Each patch is worn continuously for a week and reapplied on the same day of each week. After three weekly patches, the fourth week is patch-free, which allows menstruation. (The patch remains effective for 9 days, so being slightly late in changing it should not increase the risk for pregnancy.) In 2005, the FDA warned that the Ortho patch exposes women to higher levels of estrogen than most birth control pills, and therefore may increase the risk for blood clots and other serious side effects. Discuss with your doctor whether the patch is appropriate for you.

Vaginal Ring. A 2-inch flexible ring (NuvaRing) is available that contains both estrogen and progestin and is inserted into the vagina. Women can insert the ring by themselves once a month and take it out at the end of the third week to allow menstruation. It appears to be very effective, causing less irregular bleeding than OCs. Some women find it uncomfortable, and a few have reported vaginal irritation and discharge, but such problems rarely cause a woman to discontinue use.