Hormonal methods of birth control

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, including by mouth in a daily pill, through the skin from a patch that is changed weekly, in an injection that is given once every three months, through an implant that is worn under the skin for up to three years, and from a ring worn in the vagina for three weeks.

This topic discusses hormonal methods of birth control, including birth control pills, injectable contraception, skin patches, vaginal rings, and contraceptive implants. A discussion of long-term and barrier birth control methods are available separately. (See "Patient information: Long-term methods of birth control" and see "Patient information: Barrier methods of birth control"). An overview of all birth control methods is also available. (See "Patient information: Contraception").

CHOOSING A 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 no 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 (show table 1).

ORAL CONTRACEPTIVES — Most oral contraceptives, also referred to as "the pill," contain a combination of female hormones, estrogen and progestin (a progesterone-like medication). A list of available pills is shown in the table (show table 2). 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, OCs 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 8 percent over the first year, due primarily to missed pills or failure to restart the pill after the seven-day pill-free interval (show table 3A-3B).

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

Side effects — Side effects of the pill include: Nausea, breast tenderness, bloating, and mood changes, which typically improve after two to three months. Breakthrough bleeding or spotting. This is particularly common during the first few months of taking oral contraceptives. 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, oral contraceptives are now considered a reliable and safe option for most healthy, non-smoking women. Blood clots occur in approximately 4 women out of 10,000 using pills over a year's time. This compares to approximately one blood clot per 10,000 women who are not using pills.

The majority of studies suggest that taking (or having taken) 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 or over who smoke cigarettes (very 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)

Special concerns — Some women can take the pill, 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. Women with migraine headaches associated with visual symptoms or other neurological symptoms should not use the pill. 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.

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.

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 — The pill is taken on a 28-day cycle with 21 days of hormone pills followed by 7 days of placebo pills ("sugar pills"). 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 may experience breakthrough bleeding in the first few months. This almost always resolves without any intervention.

Continuous dosing — Some women prefer to take oral contraceptives 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 bleeding.

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 oral contraceptive product in which an active pill is taken every day for 12 weeks, followed by seven days of inactive (placebo) pills. Seasonique® is also an extended cycle oral contraceptive, although it contains seven days of a low dose estrogen pills instead of the placebo pills; this is intended to reduce breakthrough bleeding and estrogen withdrawl 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 — Two 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 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 that 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.

INJECTABLE CONTRACEPTION — The only injectable contraceptive currently available in the United States is 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 changes 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 (show table 3A-3B).

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).

TRANSDERMAL CONTRACEPTION (SKIN PATCH) — Transdermal contraceptive 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 (show table 3A-3B). However, the failure rate of the patch is greater (10 percent, as compared to 8 percent for the combination pill) for women who weigh more than 198 pounds.

Ortho Evra is the only skin patch contraceptive available in the United States. Effectiveness is similar to that of oral contraceptive pills. However, the patch appears to deliver a higher overall amount of estrogen than the pill. Some healthcare providers are concerned that this will lead to an increased risk of blood clots; further study is needed to define this risk.

The patch is worn for one week on the upper arm, shoulder, upper back, abdomen, or hip (show 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 (show picture 2A-2B). This prevents pregnancy, similar to an oral contraceptive (show table 3A-3B). 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, such as during intercourse, although it is not usually felt by the sexual partner. Risks and side effects are similar to those of oral contraceptives.

CONTRACEPTIVE IMPLANT — A single-rod progestin implant, Implanon®, has been approved for use in the US and elsewhere. It is inserted under the skin into the upper inner arm by a healthcare provider. 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.

Implanon 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.

WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. 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)
EngenderHealth

Phone: (212) 561-8000
(www.engenderhealth.org)
Planned Parenthood Federation of America

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

(www.hormone.org)


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