INTRODUCTION

Hormonal methods of birth control contain estrogen and progestin, or progestin only, and are a safe and reliable way to prevent pregnancy for most women. There are several ways that the hormone(s) can be delivered:

●A daily pill taken by mouth

●A skin patch that is changed weekly

●An injection that is given once every three months

●An implant that is worn under the skin for up to three years

●A ring worn in the vagina that is changed every month

●An intrauterine device (IUD)

This topic discusses hormonal methods of birth control, including birth control pills, injectable contraception, skin patches, vaginal rings, one type of IUD, and contraceptive implants. Nonhormonal methods, such as the copper IUD and barrier methods, are discussed separately. (See "Patient information: Long-term methods of birth control (Beyond the Basics)", section on 'Intrauterine device (IUD)' and "Patient information: Barrier methods of birth control (Beyond the Basics)".) An overview of all birth control methods is also available. (See "Patient information: Birth control; which method is right for me? (Beyond the Basics)".)

CHOOSING A BIRTH CONTROL METHOD

It can be difficult to decide which birth control method is best due to the variety of options available. The best method is one that will be used consistently, is acceptable to the woman and her partner, and which does not cause bothersome side effects. Other factors to consider include:

●Efficacy

●Convenience

●Duration of action

●Reversibility and time to return of fertility

●Effect on uterine bleeding

●Frequency of side effects and adverse events

●Affordability

●Protection against sexually transmitted diseases

No method of contraception is perfect. Each woman must balance the advantages of each method against the disadvantages and decide which method she prefers. A list of questions that are useful for defining a person's preferences are provided in the table (table 1).

BIRTH CONTROL PILLS

Most oral contraceptives, also referred to as "the pill," contain a combination of female hormones, estrogen and progestin (a progesterone-like medication). The combination pill reduces the risk of pregnancy by:

●Preventing ovulation

●Keeping the mucus in the cervix thick and impenetrable to sperm

●Keeping the lining of the uterus thin

Other non-contraceptive benefits of the pill include a reduction in:

●Menstrual cramps or pain (dysmenorrhea)

●Ovarian cancer

●Cancer of the endometrium (uterine lining)

●Acne

●Iron-deficiency anemia (a low blood count due to low iron levels)

Efficacy — When taken properly, birth control pills are a very effective form of contraception. Although the failure rate is 0.1 percent when pills are taken perfectly (same time every day, no missed pills), the actual failure rate is 9 percent over the first year, due primarily to missed pills or forgetting to restart the pill after the seven-day pill-free interval.

Missed pills are a common cause of pregnancy. In general, an active pill should be taken as soon as possible after a pill has been missed. Backup birth control should be used for seven days if more than two pills are missed.

Side effects — Possible side effects of the pill include:

●Nausea, breast tenderness, bloating, and mood changes, which typically improve within two to three months without treatment.

●Breakthrough bleeding or spotting. This is particularly common during the first few months of taking oral contraceptives. This almost always resolves without any treatment within two to three months. Forgetting a pill can also cause breakthrough bleeding.

Women taking the pill should notify their healthcare provider if they experience abdominal pain, chest pain, severe headaches, eye problems, or severe leg pain as these could be symptoms of several serious conditions including heart attack, blood clot, stroke, liver, and gallbladder disease.

Complications — When the pill was first introduced in the 1960s, the doses of both estrogen and progestin were quite high. Because of this, cardiovascular complications occurred, such as high blood pressure, heart attacks, strokes, and blood clots in the legs and lungs.

Reduced doses of progestin and estrogen in the currently available oral contraceptives have decreased these complications. Therefore, birth control pills are now considered a reliable and safe option for most healthy, non-smoking women. Blood clots occur in approximately 4 to 10 women per 10,000 using pills over a year's time. This compares to approximately 2 to 5 blood clots per 10,000 women who are not using pills and 6 to 20 blood clots per 10,000 women who are pregnant or postpartum. Older age and obesity are major risk factors for developing a blood clot whether or not the woman is taking birth control pills.

The majority of studies suggest that taking (or previously taking) the pill does not increase the risk of breast cancer.

Who should not take the pill? — Women who fall into the following categories should NOT take the pill because of an increased risk of complications:

●Aged 35 years or over who smoke cigarettes (high risk for cardiovascular complications)

●Are pregnant

●Have had blood clots or a stroke in the past, because these women are more likely to have blood clots while taking the pill

●Have a history of an estrogen-dependent tumor (eg, breast or uterine cancer)

●Have abnormal or unexplained menstrual bleeding (the cause of the bleeding should be investigated before starting the pill)

●Have active liver disease (the pill could worsen the liver disease)

●Have migraine headaches associated with visual or other neurologic symptoms (eg, aura), which increases risk of stroke

Special concerns — Some women may take the pill under certain circumstances, but need close monitoring:

●Women with high blood pressure can experience a further increase in blood pressure and should be monitored more frequently while on the pill.

●Women who take certain medication for seizures (epilepsy) and take the pill have a slightly higher risk of pill failure (pregnancy) because the seizure medicines change the way the pill is metabolized. (See 'Medication interactions' below.)

●Women with diabetes mellitus who are on the pill may need a slightly higher dose of insulin or oral diabetes medication. Women with diabetes and vascular complications from diabetes should not use the pill.

Medication interactions — The effectiveness of the pill may be reduced in women who take certain medications.

Anticonvulsants — Some anticonvulsants, including phenytoin (Dilantin), carbamazepine (Tegretol), barbiturates, primidone (Mysoline), topiramate (Topamax) and oxcarbazepine (Trileptal) decrease the effectiveness of hormonal birth control methods (pill, patch, ring). As a result, women who take these anticonvulsants are advised to avoid hormonal birth control methods (with the exception of depo-medroxyprogesterone acetate [Depo-Provera]). (See 'Injectable birth control' below.)

Other anticonvulsants do not appear to reduce contraceptive efficacy, including gabapentin (Neurontin), lamotrigine (Lamictal), levetiracetam (Keppra), and tiagabine (Gabitril). However, there is some concern that oral contraceptives may reduce the effectiveness of lamotrigine, potentially increasing the risk of seizures.

Antibiotics — Rifampin, which is sometimes used to treat tuberculosis, can decrease the efficacy of hormonal birth control. As a result, women who take rifampin should not use any hormonal birth control method (pill, patch, ring, implant, injection). Other methods (condom, diaphragm, IUD, sterilization) are recommended.

Other antibiotics (eg, penicillin, tetracycline, cephalexin) do not affect the efficacy of hormonal birth control methods. Back-up contraception is not needed when you take these antibiotics.

St. John's Wort — St. John's wort, an herbal supplement sometimes taken to treat depression, may reduce the effectiveness of birth control pills. (See "Patient information: Depression treatment options for adults (Beyond the Basics)".)

Starting the pill — Ideally, the pill should be started on the first day of the period to provide maximum contraceptive effect in the first cycle; this provides protection from pregnancy immediately.

The pill may also be started on the day it is prescribed (called "quick start), if the user is unlikely to be pregnant already. A back-up form of birth control (eg, condoms) is needed for the first seven days after the quick start.

Many women start their pill on the first Sunday after the period starts (because most pill packs are arranged for a Sunday start). Some form of back-up contraception is needed for the first seven days after the Sunday start.

When to expect a period — Traditionally, the pill is taken on a 28-day cycle with 21 days of hormone pills followed by 7 days of placebo pills ("sugar pills"). Some newer formulations have a longer duration of hormone pills and fewer days of placebo pills (eg, 24/4). It is not necessary to take the placebo pills, but some women find it easier to remember to start their next pill pack if they have taken the placebos. The period should occur during the fourth week of the pill pack, ie, the "placebo week." However, some women have irregular breakthrough bleeding or spotting in the first few months. (See 'Side effects' above.)

Continuous dosing — Some women prefer to take birth control pills continuously. This allows them to have fewer days of menstrual bleeding per year. This regimen is a particularly good treatment for women with painful periods or endometriosis, as well as those who want to avoid a monthly bleed.

Traditional birth control pill packs can be used in continuous dosing. In this regimen, the woman takes the first three weeks of a pill pack, then immediately starts a new pack (without a break); the last week of (placebo) pills is not used. This can be continued for as long as desired.

Seasonale is an extended cycle birth control regimen in which an active pill is taken every day for 12 weeks, followed by seven days of inactive (placebo) pills. Seasonique is another extended cycle pill that contains seven days of a low dose estrogen pills instead of the placebo pills; this is intended to reduce breakthrough bleeding and estrogen withdrawal symptoms.

Taking an oral contraceptive for an extended time results in fewer periods per year, although many women experience breakthrough bleeding when starting this regimen. Breakthrough bleeding is inconvenient, but does not indicate an increased risk of pill failure (unless pills are forgotten).

Shorter pill-free interval — Several pill formulations are available with 24 days of hormone pills (rather than 21) and only four days of placebo pills. It is hoped that pill failures and side effects will be minimized with this approach.

Progestin only pills — Some pills contain only progestin (called the mini pill), which is useful for women who cannot or should not take estrogen. This includes women who are breastfeeding and within 4 to 6 weeks of delivery or who have worsened migraines or high blood pressure with combination contraceptive pills. Progestin only pills are as effective as combination pills when taken at the same time every day, but there is a slightly higher failure rate of the mini pill if the woman is more than three hours late in taking it. A back up method of birth control should be used for seven days if a pill is forgotten or taken more than three hours late.

Progestin only pills are taken on a 28-day cycle, and all 28 pills contain hormone. One pill should be taken every day at the same time, and there is no placebo pill week. Breakthrough bleeding or spotting can occur with progestin only pills.

Emergency contraception — If you have sex and have forgotten to take your pill, patch, or vaginal ring, or you are more than two weeks late for your injection of medroxyprogesterone acetate, you can take a "morning after" pill to reduce the risk of pregnancy. This should be taken as soon as possible after sex, ideally within 120 hours. (See "Patient information: Emergency contraception (morning after pill) (Beyond the Basics)".)

INJECTABLE BIRTH CONTROL

The only injectable contraceptive currently available in the United States is depot medroxyprogesterone acetate or DMPA (Depo-Provera). DMPA is injected deep into a muscle, such as the buttock or upper arm, once every three months. A preparation that is given subcutaneously (under the skin) is also available.

DMPA prevents ovulation and thickens the cervical mucus, making the cervix impenetrable to sperm. If the first dose of DMPA is given during the first seven days of the menstrual period, it prevents pregnancy immediately. A woman who receives her first DMPA injection after the seventh day of her period should use a second form of contraception (eg, condoms) for seven days. DMPA is very effective, with a failure (pregnancy) rate of less than one percent when the injection is given on time.

Side effects — The most common side effects of DMPA are irregular or prolonged bleeding and spotting, particularly during the first few months of use. Up to 50 percent of women completely stop having menstrual periods (amenorrhea) after one year of DMPA use. Menses generally return within six months of the last DMPA injection. DMPA is associated with weight gain in some women.

In women who use injectable progestins, there is no increased risk of cardiovascular complications or cancer. Use of DMPA is associated with decreased bone mineral density in current users. This effect is mostly reversed after DMPA is stopped. Studies have not shown an increased risk of bone fractures in women who have used DMPA in the past.

Because DMPA is long-acting, it may not be ideal for women who wish to become pregnant shortly after stopping the medication. Although most women are able to conceive within 10 months, fertility may not return for up to 18 months after the last injection.

There are a number of women who prefer DMPA to the pill, including those who:

●Have difficulty remembering to take a pill every day

●Cannot use estrogen

●Also take seizure medications, which can be less effective with combination hormonal contraceptives.

Additional benefits of DMPA include a decreased risk of uterine cancer and pelvic inflammatory disease (PID).

BIRTH CONTROL SKIN PATCH

Birth control skin patches contain estrogen and progestin, similar to oral contraceptives. The patch is as effective as oral contraceptives, and may be preferred by some women because it does not require daily dosing. However, the failure rate of the patch is higher for obese women (eg, who weigh more than 198 pounds).

Xulane is the only skin patch contraceptive available in the United States. Effectiveness is similar to that of oral contraceptive pills. However, the patch may deliver a higher overall dose of estrogen than the pill. Some studies found that this was associated with an approximate doubling of the risk of blood clots while others found no increase in risk. Further study is needed to define this risk.

The patch is worn for one week on the upper arm, shoulder, upper back, abdomen, or buttock (picture 1). After one week, the old patch is removed and a new patch is applied; this is done for three weeks. During the fourth week, no patch is worn; the menstrual period occurs during this week.

VAGINAL RING

Nuvaring is a flexible plastic vaginal ring that contains estrogen and a progestin, which is slowly absorbed through the vaginal tissues (picture 2A-B). This prevents pregnancy, similar to an oral contraceptive. It is worn in the vagina for three weeks, followed by one week when no ring is used; a menstrual period occurs during this time. The ring's position inside the vagina is not important.

Most women cannot feel the ring, and it is easy to insert and remove. It may be removed for up to three hours if desired, but should be left in during intercourse (the ring is not usually felt by the sexual partner). If the ring is left out for more than three hours, the woman may be able to put it back in, or may need to discard it, depending on where she is in her cycle:

●During the first two weeks of the cycle, the ring can be reinserted and the woman can continue with the usual schedule. The ring should be rinsed in cool or warm (but not hot) water before it is reinserted.

●During the third week, the woman can insert a new ring and begin a new cycle immediately. If the ring was previously in place for at least seven days in a row, the woman can also choose to leave the ring out for up to a week (during which she may have her period) and then insert a new one.

Regardless of where the woman is in her cycle, if the ring is left out for more than three hours, a backup method of birth control (eg, condoms) should be used for the next seven days.

Risks and side effects are similar to those of oral contraceptives. There is scientific controversy regarding the progestin hormone in the ring, and whether it also may be associated with a higher risk of blood clots, approximately double, such as with the patch.

BIRTH CONTROL IMPLANT

A single-rod progestin implant, Implanon or Nexplanon, has been approved for use in the United States and elsewhere. It is inserted under the skin into the upper inner arm by a healthcare provider (picture 3). It is effective for up to three years, but can be removed if pregnancy is desired sooner. Insertion and removal can be done in an office or clinic.

The implant is one of the most effective methods of birth control. It provides three years of protection from pregnancy as progestin is slowly absorbed into the surrounding tissues. It is effective within 24 hours of insertion. Irregular bleeding is the most bothersome side effect. Fertility returns rapidly after removal of the rod.

IUD WITH PROGESTIN

There are three intrauterine devices (IUDs) that contain a hormone, called levonorgestrel. One is called Mirena (in the United States) and can be left in place for up to five years. A device similar to Mirena (containing the same amount of hormone) is called Liletta and is approved for three years, but will likely be extended for up to five years of use like Mirena. The third option is called Skyla and can be left in place for up to three years. All are highly effective in preventing pregnancy. A complete discussion of IUDs is available separately. (See "Patient information: Long-term methods of birth control (Beyond the Basics)".)

PREGNANCY AFTER HORMONAL BIRTH CONTROL

The length of time it takes to become pregnant after use of a hormonal method of birth control depends upon which method was used, as well as some individual factors.

Most women are able to become pregnant immediately. For some, it may take several months before ovulation becomes regular and the woman can become pregnant, especially if the her periods were irregular before she used birth control. However, hormonal birth control does not increase the risk of infertility.

●Women who use combination estrogen-progestin methods (eg, birth control pill, skin patch, vaginal ring) usually begin to ovulate regularly one to three months after stopping. In one study, the median time for a woman to have a menstrual period after stopping the continuous pill was 32 days, and 185 of 187 women (98.9 percent) had a menstrual period or became pregnant within 90 days [1].

●With injectable depot medroxyprogesterone acetate (DMPA or Depo-Provera), return of fertility can be delayed. Fifty percent of women will become pregnant within 10 months of the last injection. In a small number of women, however, it may take up to 18 months after the last injection to conceive. Women with lower body weights tend to become pregnant sooner than women with higher body weights after discontinuing DMPA.

●Women who use contraceptive implants (eg, Implanon) usually begin to ovulate again within one month after the device is removed.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient information: Hormonal birth control (The Basics)
Patient information: Choosing birth control (The Basics)
Patient information: Endometriosis (The Basics)
Patient information: Ovarian cysts (The Basics)
Patient information: Premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD) (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient information: Long-term methods of birth control (Beyond the Basics)
Patient information: Barrier methods of birth control (Beyond the Basics)
Patient information: Birth control; which method is right for me? (Beyond the Basics)
Patient information: Depression treatment options for adults (Beyond the Basics)
Patient information: Emergency contraception (morning after pill) (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Intrauterine contraception: Devices, candidates, and selection
Contraception: Overview of issues specific to adolescents
Depot medroxyprogesterone acetate for contraception
Emergency contraception
Female condoms
Fertility awareness-based methods of pregnancy prevention
Hormonal contraception for suppression of menstruation
Diaphragm, cervical cap, and sponge
Male condoms
Contraceptive counseling and selection
Overview of the use of estrogen-progestin contraceptives
Progestin-only pills (POPs) for contraception
Risks and side effects associated with estrogen-progestin contraceptives

The following organizations also provide reliable health information.

●National Library of Medicine

     (www.nlm.nih.gov/medlineplus/healthtopics.html)

●National Institute of Child Health and Human Development (NICHD)

     Toll-free: (800) 370-2943
     (www.nichd.nih.gov)

●National Women's Health Resource Center (NWHRC)

     Toll-free: (877) 986-9472
     (www.healthywomen.org)

●Planned Parenthood Federation of America

     Phone: (212) 541-7800
     (www.plannedparenthood.org)

●The Hormone Foundation

      (www.hormone.org)

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All topics are updated as new information becomes available. Our peer review process typically takes one to six weeks depending on the issue.