Contraceptive hormones can be
The hormones used to prevent conception include estrogen and progestins (drugs similar to the hormone progesterone). Hormonal methods prevent pregnancy mainly by stopping the ovaries from releasing eggs or by keeping mucus in the cervix thick so that sperm cannot pass through the cervix into the uterus. Thus, hormonal methods prevent the egg from being fertilized.
All hormonal methods can have similar side effects and restrictions on use.
Oral contraceptives, commonly known as birth control pills or just “the pill,” contain hormones—either a combination of a progestin and estrogen or a progestin alone.
Combination tablets (tablets that contain both estrogen and progestin) are typically taken once a day for 21 to 24 days, not taken for 4 to 7 days (allowing the menstrual period to occur), then started again. Inactive (placebo) tablets are usually taken for the days when combination tablets are not taken to establish a routine of taking one tablet a day. The inactive tablet may contain iron and folate. Iron is included to help prevent or treat iron deficiency because iron is lost in menstrual blood each month. Folate is included in case women, who may unknowingly have a folate deficiency, become pregnant. Folate deficiency in a pregnant woman increases the risk of birth defects such as spina bifida.
Other combination contraceptives have different schedules. One product is taken daily for 12 weeks, then not taken for 1 week. Thus, menstrual periods occur only 4 times a year. Another product involves taking an active tablet every day. With this product, there is no scheduled bleeding (no menstrual periods), but irregular bleeding is more likely to occur.
About 0.3% of women who take combination tablets as instructed become pregnant during the first year of use. However, the chances of becoming pregnant increase substantially if women skip or forget to take a tablet, especially the first ones in a monthly cycle. With typical use (the way most people use them), about 9% of women become pregnant during the first year of use.
The dose of estrogen in combination tablets varies. Usually, combination tablets with a low dose of estrogen (10 to 35 micrograms) are used because they have fewer serious side effects than those with a high dose (50 micrograms). Healthy women who do not smoke can take low-dose combination tablets until menopause.
If women miss taking a combination tablet one day, they should take two tablets the next day. If they forget to take a tablet for 2 days, they should resume taking one tablet each day and should use a backup contraceptive method for the next 7 days. If women forget to take a tablet for 2 days and have had unprotected intercourse in the 5 days before those 2 days, they can consider emergency contraception.
Progestin-only tablets are taken every day of the month at the same time of day. They often cause irregular bleeding. Pregnancy rates with these tablets and with combination tablets are similar. Progestin-only tablets are usually prescribed only when taking estrogen may be harmful. For example, these tablets may be used by women who have migraines with an aura (symptoms that occur before the headache), high blood pressure, or severe diabetes (see Conditions That Prohibit the Use of Combination Oral Contraceptives). If more than 27 hours go by between tablets, women should use a backup contraceptive method for the next 7 days in addition to taking the progestin-only contraceptive each day.
Before starting oral contraceptives, a woman must see a doctor. Doctors ask the woman about her medical, social, and family history to determine whether she has any health problems that would make taking these contraceptives risky for her. They measure her blood pressure. If it is high, combination oral contraceptives ( estrogen plus a progestin) should not be prescribed. A pregnancy test is done to rule out pregnancy. Doctors also often do a physical examination, although this examination is not necessary before a woman starts taking oral contraceptives. Three months after starting oral contraceptives, the woman should have another examination to determine whether her blood pressure has changed. If it has not, she should then have an examination once a year. Oral contraceptives can be prescribed for 13 months at a time.
Women can start taking oral contraceptives at any time of month. However, if they start taking them more than 5 days after the first day of their period, they should use a backup contraceptive method for the next 7 days in addition to taking the oral contraceptive.
When women can start taking combination oral contraceptives after pregnancy varies:
After a miscarriage or an abortion during the 1st trimester of pregnancy: Start immediately
After a miscarriage, delivery, or an abortion during the 2nd trimester: Start within 1 week
For a delivery after 28 weeks: Wait 21 days
If women are breastfeeding or have risk factors for blood clots (such as being obese or having had a cesarean delivery): Wait 42 days
Women with risk factors for blood clots should wait because blood clots are more likely to develop during pregnancy and after delivery. Taking combination oral contraceptives also makes blood clots more likely to develop.
Progestin-only oral contraceptives may be taken immediately after the delivery of a baby.
In most women who are exclusively breastfeeding and who have not had a menstrual period, pregnancy is unlikely to occur for 6 months after the baby is delivered, even when no contraception is used. However, starting to use contraception within 3 months after delivery is usually recommended.
If a woman has coronary artery disease or diabetes or has risk factors for them (such as a close relative with either disorder), a blood test is usually done to measure levels of cholesterol, other fats (lipids), and sugar (glucose). Even if these levels are abnormal, doctors may still prescribe a low-dose estrogen combination contraceptive. However, they periodically do blood tests to monitor the woman’s lipid and sugar levels. Women with diabetes can usually take combination oral contraceptives unless diabetes has damaged blood vessels or they have had diabetes for more than 20 years.
If women have had a liver disorder, doctors do tests to evaluate how well the liver is functioning. If results are normal, women can take oral contraceptives.
Also before starting oral contraceptives, a woman should talk with her doctor about the advantages and disadvantages of oral contraceptives for her situation.
The main advantage is reliable, continuous contraception if oral contraceptives are taken as instructed.
Also, taking oral contraceptives reduces the occurrence of the following:
Premenstrual dysphoric disorder (the severe form of premenstrual syndrome)
Abnormal uterine bleeding due to ovulatory dysfunction (abnormal bleeding that results from changes in the hormonal control of menstruation)
Mislocated (ectopic) pregnancies (almost always in the fallopian tubes)
Infections of the fallopian tubes
Cancer of the uterus (endometrial cancer)
The risk of developing cancer of the uterus and cancer of the ovaries is reduced for at least 20 years after the contraceptives are stopped.
Oral contraceptives taken early in a pregnancy do not harm the fetus. However, they should be stopped as soon as the woman realizes she is pregnant. Oral contraceptives do not have any long-term effects on fertility, although a woman may not release an egg (ovulate) for a few months after stopping the drugs.
The disadvantages may include bothersome side effects.
Breakthrough bleeding is common during the first few months of oral contraceptive use, particularly if women forget to take the tablets, but it usually stops as the body adjusts to the hormones. Breakthrough bleeding is bleeding that occurs between periods, when women are taking the active pill. If breakthrough bleeding persists, doctors may increase the dose of estrogen.
Some side effects are related to the estrogen in the tablet. They may include nausea, bloating, fluid retention, an increase in blood pressure, breast tenderness, and migraine headaches. Others, such as acne and changes in appetite and mood, are related mostly to the type or dose of the progestin. Some women who take oral contraceptives gain 3 to 5 pounds because they retain fluid or because appetite increases. Many of these side effects are uncommon with the low-dose tablets.
Oral contraceptives can also cause vomiting, headaches, depression, and problems sleeping.
In some women, oral contraceptives cause dark patches (melasma) on the face, similar to those that may occur during pregnancy. Exposure to the sun darkens the patches even more. If dark patches develop, women should discuss stopping the oral contraceptives with their doctor. The patches slowly fade after the contraceptives are stopped.
Taking oral contraceptives increases the risk of developing some disorders.
The risk of developing blood clots in veins may be 2 to 4 times higher for women who are taking combination oral contraceptives than it was before they started taking the contraceptives. However, this risk is much less than the risk of developing blood clots during pregnancy. Women with family members who have had blood clots should not take oral contraceptives that contain estrogen. If doctors suspect that a woman taking oral contraceptives has deep vein thrombosis or pulmonary embolism, the contraceptives are stopped immediately. Tests are then done to confirm or rule out the diagnosis. Because being immobilized for a long time also increases the risk of developing blood clots, women should stop taking oral contraceptives at least 1 month before major elective surgery and not take them again until 1 month afterward. If surgery requires only minimal immobilization (as for minor outpatient surgery or laparoscopic surgery), stopping oral contraceptives is not necessary.
Cervical cancer is slightly more likely to develop in women who use oral contraceptives for more than 5 years. But 10 years after stopping use, this risk decreases to what it was before starting oral contraceptives. Also, whether the increased risk is related to the oral contraceptives is unclear. Women who are taking oral contraceptives should have Papanicolaou (Pap) tests as recommended by their doctor. Such tests can detect precancerous changes in the cervix early—before they lead to cancer.
If women developed jaundice due to reduced or slow movement of bile through the bile ducts (cholestasis) during a previous pregnancy, they may have the same problem when they take oral contraceptives. They may still be able to take oral contraceptives, but they should have regular examinations and blood tests to check for this problem. However, if women developed jaundice when they took oral contraceptives in the past, they should not take them again.
Gallstones are not more likely to form in women who take low-dose oral contraceptives.
The risk of having a heart attack is increased if women who are older than 35 and who smoke take oral contraceptives. Typically, such women should not use oral contraceptives.
If women have a high triglyceride (a fat) level, taking combination oral contraceptives can increase the level even more. A high triglyceride level may increase the risk of a heart attack or stroke in people who have other risk factors for these disorders. Oral contraceptives increase the risk of blood clots (which can also contribute to heart attacks and strokes). So, women with a high triglyceride level should not take combination oral contraceptives.
Rarely, a noncancerous liver tumor (hepatocellular adenoma) develops. If this tumor suddenly ruptures and bleeds into the abdominal cavity, emergency surgery is required. However, such bleeding is rare. Taking oral contraceptives for a long time and in high doses increases the risk of developing this tumor. The tumor usually disappears after oral contraceptives are stopped.
Taking certain drugs can make oral contraceptives less effective. These drugs include the following:
If women taking oral contraceptives have to take one of these drugs, they should also use another contraceptive method while they are taking the drug, and they should continue using another contraceptive method until their first period occurs after they stop the drug. Women should not take lamotrigine (an antiseizure drug) with oral contraceptives. Oral contraceptives may make lamotrigine less effective in controlling seizures.
A woman must not take combination oral contraceptives (tablets that contain estrogen and a progestin) if any of the following conditions are present:
She must not take them within 21 days after having a baby or, if she has risk factors for developing blood clots, within 42 days after having a baby. Risk factors include being obese or having had a cesarean delivery.
She smokes more than 15 cigarettes a day and is older than 35.
She has or has had breast cancer.
She has migraines and is older than 35, or she has migraines with an aura (symptoms that occur before the headache, such as seeing jagged, shimmering, or flashing lights or having unusual sensations in the skin).
She has a very high triglyceride level.
She has untreated or poorly controlled high blood pressure.
She has had diabetes for more than 20 years or has diabetes that has damaged blood vessels, such as those in the eyes (causing loss of vision).
She has coronary artery disease.
She has a heart valve disorder that is causing problems.
Her heart was damaged during a previous pregnancy (called peripartum cardiomyopathy).
She has had an organ transplant that is causing problems.
She has active lupus (systemic lupus erythematosus) or risk factors for developing blood clots related to lupus.
Oral contraceptives do not increase the risk of breast cancer in women who are currently taking them, in women aged 35 to 65 who used to take them, or in women who have certain benign breast disorders or a family history of breast cancer.
For healthy women who do not smoke, taking low-dose combination tablets with a low dose of estrogen does not increase the risk of having a stroke or heart attack.
Skin patches and vaginal rings contain estrogen and a progestin. They should be used for 3 weeks, then not used for 1 week to allow the menstrual period to occur. If women do not start using the patch or ring during the first 5 days of their period, they must use a backup method of birth control during the first 7 days that they use the patch or ring.
Contraceptive skin patches and vaginal rings are effective. About 0.3% of women who use one of these methods as instructed become pregnant during the first year of use. With typical use (the way most people use them), about 9% become pregnant during the first year. Effectiveness is similar to that of oral contraceptives. The patch may be less effective in overweight women than in women with a lower weight.
A contraceptive skin patch is attached to the skin with an adhesive. It should be left in place for 1 week, then removed and replaced with a new patch, which is placed on a different area of the skin. A new patch is applied once a week (on the same day each week) for 3 weeks, followed by a week when no patch is used.
If more than 2 days go without using the patch, women should use a backup contraceptive method for 7 days in addition to the patch. If 2 days go by and women have had unprotected intercourse in the 5 days before those 2 days, they can consider emergency contraception.
Exercise and use of saunas or hot tubs do not displace the patch.
Skin under and around the patch may become irritated.
A vaginal ring is a small flexible, soft, transparent device that is placed in the vagina.
Two types of rings are available:
Both types are left in place for 3 weeks, then not used for 1 week to allow the menstrual period to occur.
A woman can place and remove the vaginal ring herself. The ring comes in one size and can be placed anywhere in the vagina.
If the ring is removed for more than 3 hours, women should use a backup contraceptive method for 7 days in addition to the ring.
Usually, the vaginal ring is not felt by the woman’s partner during intercourse. The ring does not dissolve and cannot be pushed too far up.
If women use a patch or a ring for 3 weeks (replacing it each week), followed by 1 week when no patch or ring is used, they typically have a regular menstrual period. Spotting or bleeding between periods (breakthrough bleeding) is uncommon. Irregular bleeding becomes more common the longer women use the patch or ring.
Side effects, effects on the risk of developing disorders, and restrictions on use are similar to those of combination oral contraceptives.
A contraceptive implant is a single match-sized rod containing a progestin. The implant releases the progestin slowly into the bloodstream. The type of implant available in the United States is effective for 3 to 5 years.
Only a very small percentage (about 0.05%) of women become pregnant during the first year of use.
After numbing the skin with an anesthetic, a doctor uses a needle-like instrument (trocar) to place the implant under the skin of the inner arm above the elbow. No incision or stitches are necessary. Doctors must receive special training before they can do this procedure.
If women have not had unprotected sex since their last period, an implant can be inserted at any time during the menstrual cycle. If women have had unprotected sex, they should use another form of contraception until their next menstrual period occurs or until a pregnancy test is done and rules out pregnancy. If women are not pregnant, the implant can be inserted. An implant can also be inserted immediately after a miscarriage, an abortion, or delivery of a baby.
If the implant is not inserted within 5 days after a woman's periods starts, she should use a backup contraceptive method for 7 days in addition to the implant.
The most common side effects are irregular or no menstrual periods and headaches. These side effects prompt some women to have the implant removed. Because the implant does not dissolve in the body, a doctor has to make an incision in the skin to remove it. Removal is more difficult than insertion because tissue under the skin thickens around the implant.
As soon as the implant is removed, the ovaries return to their normal functioning, and women become fertile again.
A progestin called medroxyprogesterone acetate is injected by a health care practitioner once every 3 months. Two types of contraceptive injections are available.
Each type is very effective. If women get the injections as instructed, only about 0.2% of them become pregnant during the first year of use. With typical use (the way most people use it—with delays between injections), about 6% become pregnant.
An injection may be given immediately after a miscarriage, an abortion, or delivery of a baby. If the interval between injections is more than 4 months, a pregnancy test is done to rule out pregnancy before the injection is given. If women do not get the first injection within 5 to 7 days after their period starts, they must use a backup method of contraception for 7 days after they get the injection.
The progestin completely disrupts the menstrual cycle. About one third of women using this contraceptive have no menstrual bleeding during the 3 months after the first injection, and another third have irregular bleeding and spotting for more than 11 days each month. After this contraceptive is used for a while, irregular bleeding occurs less often. After 2 years, about 70% of the women have no bleeding at all. When the injections are stopped, a regular menstrual cycle resumes in about half the women within 6 months and in about three fourths within 1 year. Fertility may not return for up to 18 months after injections are stopped.
Women typically gain 3 to 9 pounds during the first year of use and continue to gain weight. To prevent this gain, women need to limit calories and increase the amount of exercise they do.
Headaches are common, but they usually become less severe over time. If women have had tension headaches and migraines in the past, the injections do not make them worse.
Bone density temporarily decreases. However, the risk of fractures does not increase, and bones usually return to their previous density after the injections are stopped. Getting enough calcium and vitamin D daily to help maintain bone density is important for all women, but it is particularly important for adolescent and young women who are getting progestin injections. Calcium and vitamin D supplements are often needed to get the required amount.
Medroxyprogesterone acetate does not increase the risk of developing breast, ovarian, or invasive cervical cancer.
It reduces the risk of developing
Interactions with other drugs are uncommon.
Unlike combination oral contraceptives, progestin injections do not increase the risk of high blood pressure or blood clots.
Medroxyprogesterone acetate is currently considered safe for women who should not take estrogen and may be a good choice for women with a seizure disorder.