Decisions about contraception for women with underlying medical problems can be complicated. Although several studies have shown that the use of hormonal contraceptives is safe and effective in healthy women, there are much fewer data concerning their use in women with medical problems. In some women, drugs taken for certain chronic conditions may alter the effectiveness of hormonal contraceptives; in such cases, pregnancy may be especially risky for the mother and fetus. The American College of Obstetricians and Gynecologists (ACOG) reviewed the evidence on the use of hormonal contraceptives in women with underlying medical conditions.

Women with Cardiovascular Risk Factors

ACOG addressed the use of combination oral contraceptives and other forms of hormonal contraception in women with hypertension, dyslipidemia, and diabetes; women who smoke or are obese; and women older than 35 years.

HYPERTENSION

Studies have shown that the use of oral contraceptives (including newer agents) increases blood pressure by as much as 8 mm Hg systolic and 6 mm Hg diastolic. However, depot medroxyprogesterone acetate (DMPA; Depo-Provera) does not significantly affect blood pressure. Some studies have reported increases in the risk of vascular events in women taking combination estrogen/progestin contraceptives. Because of the increased risk of myocardial infarction (MI) and stroke in women with hypertension, and the likelihood of additional risks associated with hormonal contraceptives, the decision to use combination hormonal contraceptives in these women should be weighed against the risk of adverse pregnancy outcomes associated with hypertension.

In women with well-controlled and monitored hypertension who are 35 years or younger, a trial of combination contraceptives may be appropriate as long as the patient is otherwise healthy, shows no signs of end-organ vascular disease, and does not smoke. If blood pressure remains well controlled several months after the trial is started, combination contraceptives may be continued. Progestin-only contraceptives and the levonorgestrel-releasing intrauterine system (Mirena) are appropriate options in women with hypertension.

DYSLIPIDEMIA

The estrogen component of combination oral contraceptives enhances removal of low-density lipoprotein (LDL) cholesterol and increases levels of high-density lipoprotein (HDL) cholesterol. Oral estrogen also increases triglyceride levels, but in women with both increased HDL and decreased LDL levels, this moderate increase in triglyceride levels does not increase the risk of atherogenesis. The progestin component of combination oral contraceptives antagonizes these estrogen-induced lipid changes. Therefore, the choice and dose of progestin in combination oral contraceptives may affect the overall change in lipid levels; formulas with less androgenic progestins increase HDL levels more and triglyceride levels less than formulas with more androgenic progestins. The effects of combination estrogen/progestin pills, as well as those of other hormonal contraceptives, are presented in Table 1.

Because the absolute risk of cardiovascular events is low in women with controlled dyslipidemia, most of these women can use combination oral contraceptives with 35 mcg or less of estrogen. Fasting serum lipid levels should be monitored often after combination oral contraceptives are initiated in women with dyslipidemia; less frequent monitoring is appropriate once lipid parameters have stabilized. Alternative contraceptives should be considered for women with uncontrolled LDL levels greater than 160 mg per dL (4.14 mmol per L) or multiple cardiovascular risk factors. The use of progestin-only contraceptives does not increase the risk of MI.

DIABETES

Studies have shown that the use of combination oral contraceptives does not increase a woman's risk of developing type 2 diabetes. In women with type 1 diabetes, the use of combination oral contraceptives does not seem to impair metabolic control or accelerate the development of vascular disease. However, because of theoretical concerns, ACOG recommends that the use of combination oral contraceptives be limited to nonsmoking, otherwise healthy women with diabetes who are younger than 35 years and show no evidence of hypertension, nephropathy, retinopathy, or other vascular disease. The levonorgestrel-releasing intrauterine system also is an appropriate option in women with diabetes.

SMOKING

Epidemiologic and case-control studies from the past 40 years have produced inconsistent evidence as to whether oral contraceptives increase the risk of MI in women who smoke. Because of the limited amount of conclusive data, ACOG recommends that physicians prescribe combination oral contraceptives with caution, if at all, in women older than 35 years who smoke.

OBESITY

Obesity (i.e., body mass index of at least 30 kg per m²) may impair the effectiveness of combination oral and transdermal contraceptives. However, the incrementally higher failure rates in these patients should not exclude the use of these contraceptives in favor of less effective methods.

Obesity and the use of combination oral contraceptives are independent risk factors for venous thromboembolism. Thus, consideration should be given to progestin-only and intrauterine contraceptives when counseling obese women about their options. Because obese women have an elevated risk of dysfunctional uterine bleeding and endometrial neoplasia, the use of the levonorgestrel-releasing intrauterine system may be a beneficial choice in these women.

WOMEN OLDER THAN 35 YEARS

The use of combination oral contraceptives with less than 50 mcg of estrogen is safe in healthy, nonsmoking women older than 35 years and may have a beneficial effect on bone mineral density and vasomotor symptoms in perimenopausal women. The reduced risk of endometrial and ovarian cancers associated with oral contraceptive use is of particular importance to older women of reproductive age. However, these benefits must be balanced against the cardiovascular risk factors of obesity and age, particularly as they relate to the risk of venous thromboembolism. Because of this risk, the use of combination contraceptives should be individualized in women older than 35 years.

Women with Obstetric and Gynecologic Considerations

ACOG addressed the use of combination oral contraceptives and other forms of hormonal contraception in women with an increased risk of breast cancer, women with uterine fibroid tumors, and women who are postpartum or lactating.

BREAST CANCER

Women with fibroadenoma, benign breast disease with epithelial hyperplasia, or a family history of breast cancer have an increased risk of breast cancer. The risk of benign breast disease is lower in women who use oral contraceptives compared with nonusers. Studies have found that a slightly increased risk of breast cancer is associated with current or recent use of oral contraceptives, but that oral contraceptive use does not further increase risk in women with a family history of breast cancer or a personal history of benign breast disease.

The use of oral contraceptives before age 30 and use for more than five years are associated with an increased risk of breast cancer in women with the BRCA1 gene, but not in those with the BRCA2 gene. Because oral contraceptive use reduces the risk of ovarian cancer, these drugs offer significant benefits for women with BRCA mutations.

UTERINE FIBROID TUMORS

Combination oral contraceptives reduce menstrual blood loss in women with normal menses and those with menorrhagia. Oral contraceptives also reduce dysmenorrhea and may decrease bleeding disorders in women with uterine fibroid tumors. Studies have found that DMPA lowers the risk of uterine fibroid tumors, reduces bleeding in women who have such tumors, and decreases the need for hysterectomy to treat this condition. The levonorgestrel-releasing intrauterine system also reduces menorrhagia associated with uterine fibroid tumors.

POSTPARTUM AND LACTATING WOMEN

Women remain in a hypercoagulable condition for weeks after childbirth. Product labeling for combination oral contraceptives advises deferring their use until four weeks postpartum in nonbreastfeeding women. Because DMPA and progestin-only contraceptives do not contain estrogen, these methods may be safely initiated immediately after delivery.

The use of combination oral contraceptives in well-nourished breastfeeding women does not result in infant developmental problems, and these drugs may be initiated once milk flow is established. DMPA and progestin-only contraceptives do not impair infant development or lactation and, in fact, may increase the quality and duration of lactation. Because DMPA and progestin-only pills do not have a procoagulation effect and are safe in breastfeeding women, their use at six weeks postpartum in lactating women and immediately after delivery in nonlactating women is reasonable.

Women with Other Medical Conditions

ACOG also addressed the use of combination oral contraceptives and other forms of hormonal contraception in women with migraine headaches, systemic lupus erythematosus, sickle cell disease, and a history of venous thromboembolism.

The use of combination contraceptives may be considered in women with migraine headaches if they do not have focal neurologic signs, do not smoke, are otherwise healthy, and are younger than 35 years. Although cerebrovascular events are rare in women with migraine headaches who take combination oral contraceptives, physicians should consider the use of progestin-only, intrauterine, or barrier methods of contraception.

Combination oral contraceptives are safe in women with mild lupus who do not have antiphospholipid antibodies or histories of vascular disease or nephritis. Progestin-only methods are safe alternatives.

No well-controlled study has assessed whether venous thromboembolism risk is increased in women with sickle cell disease who take oral contraceptives. However, the consensus is that pregnancy carries a greater risk than does the use of combination oral contraceptives. DMPA has noncontraceptive benefits and is an appropriate choice in women with sickle cell disease.

Combination contraceptives are not recommended in women with a history of unexplained venous thromboembolism unless they are taking anticoagulants. Patients who years earlier experienced a single episode of venous thromboembolism associated with a nonrecurring risk factor (e.g., after immobilization following a motor vehicle crash) may not be at increased risk of venous thromboembolism, and the decision to initiate combination oral contraceptives can be individualized.

Women Taking Concomitant Medications

Serum progestin levels in women using progestin-only oral contraceptives and implants are lower than those in women using combination oral contraceptives. Accordingly, low-dose progestin-only contraceptives should not be used in women taking concomitant liver enzyme inducers. The levonorgestrel-releasing intrauterine system remains effective when anticonvulsants and other liver enzyme–inducing medications are taken. The effectiveness of DMPA in women taking liver enzyme inducers has not been studied.

ANTICONVULSANTS

Anticonvulsants that induce liver enzymes can decrease serum concentrations of either component of combination oral contraceptives (Table 2). Although reduced serum levels of oral contraceptive steroids have been noted in women who also were taking anticonvulsants, ovulation or accidental pregnancy did not occur.

Some physicians prescribe oral contraceptives containing 50 mcg of ethinyl estradiol to women taking liver enzyme–inducing anticonvulsants and other medications that reduce serum steroid levels. However, no published data support the enhanced contraceptive effectiveness of this practice. Although it seems prudent to use 30 to 35 mcg of estrogen rather than 20 to 25 mcg in women taking medications that reduce serum steroid levels, no data support this recommendation. The use of condoms in combination with oral contraceptives or the use of an intrauterine device may be considered in such women.

ANTIBIOTICS

Although there have been many anecdotal reports of oral contraceptive failure in women taking concomitant antibiotics, rifampin (Rifadin) is the only antibiotic that has been proven to decrease serum steroid levels (Table 3). Because serum steroid levels are significantly reduced in women taking rifampin, they should not rely on combination oral contraceptives, progestin-only contraceptives, or implants for contraception.

ANTIRETROVIRALS

Data from several small studies suggest that serum steroid levels in oral contraceptive users may be affected by the use of various antiretroviral medications (Table 4). However, no clinical outcome studies have been performed, so the practical implications of these data are unknown.