Medical Disorders and Contraception
WHEC Practice Bulletin and Clinical Management Guidelines for healthcare providers.
Educational grant provided by Women's Health and Education Center (WHEC).
Decisions regarding contraception for women with coexisting medical problems may be complicated. In some cases, medications taken for certain chronic conditions may alter the effectiveness of hormonal contraception, and pregnancy in these cases may pose substantial risks to the mother as well as her fetus. In addition, differences in content and delivery methods of hormonal contraceptives may affect patients with certain conditions differently. When selecting one of the many effective contraceptive methods available, healthcare providers and women need to consider each method's risk/benefit profile relative to the specific underlying illness. Although numerous studies have addressed the safety and effectiveness of hormonal contraceptive use in healthy women, data are far less complete for women with underlying medical disorders or other special circumstances. All contraceptive methods currently available in the United States are generally safe for use by healthy, non-smoking women and pose only minimal health risks overall. At the same time, the preexisting condition is itself likely to increase the risks of maternal and fetal complications, morbidity, and mortality inherent in any pregnancy. Risks of pregnancy in women with certain medical conditions are generally greater than risks associated with contraceptive use (1).
The purpose of this document is to provide information to help healthcare providers and women with coexisting medical conditions make sound decisions regarding the selection and appropriateness of various hormonal contraceptives and facilitate use of contraceptive choices that do not exacerbate medical problems. Addressed in this document are; to recognize that increased risks are associated with pregnancy in women with various medical conditions and evaluate evidence-based risks and benefits of use of intrauterine devices (IUDs) in women with various medical conditions.
Use of combination oral contraceptives is safe in healthy, non-smoking women older than 35 years. Large U.S. population-based case-control studies have found no increased risk of myocardial infarction or stroke among healthy, non-smoking women older than 35 years who use oral contraceptives formulated with less than 50 mcg of estrogen (5). Premenstrual women may benefit from a positive effect on bone mineral density and a reduction in vasomotor symptoms offered by combination oral contraceptives. In addition, 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 impact of age and obesity as independent risk factors for cardiovascular disease. In particular, it is important to note that the background risk of venous thromboembolism (VTE) increases with age, and therefore, the role of venous thromboembolism attributable to combination contraception use increases substantially for women aged 40 years and older. Because this risk increases sharply after age 39 years among combination oral contraceptive users, combination contraceptive use should be individualized in women older than 35 years; in particular, caution should be exercised for those who are obese or who have other cardiovascular disease risks.
Efficacy/Safety of Contraceptives in Various Medical Conditions
Steroids in combination oral contraceptives might impair carbohydrate metabolism and accelerate the occurrence of vascular disease in women with diabetes. However, current combination oral contraceptives do not appear to have this effect. In women either type 1 or type 2 diabetes without vascular disease, use of combination hormonal contraception does not adversely affect metabolic control, promote vascular disease or increase risk of cardiovascular disease (CVD). Use of combination hormonal contraceptive methods does not increase risk of type 2 diabetes in women with prior gestational diabetes (2). In women with diabetes with vascular involvement, use of combination hormonal contraceptive methods is contraindicated. Based on theoretical concerns, the American College of Obstetricians and Gynecologists (ACOG) recommends that use of combination hormonal contraceptives in women with diabetes should be limited to non-smoking, otherwise healthy women who are younger than 35 and have no evidence of hypertension, nephropathy, or retinopathy. For women with diabetes, with or without vascular disease or hypertension use of intrauterine contraceptive devices (IUDs) or progestin-only contraceptive methods or barrier methods is not contraindicated.
Use of oral contraceptives appears to increase blood pressure, even with contemporary oral contraceptive preparations. A systemic review of 22 articles published through February 2005 describing 13 studies of combination oral contraceptives use and CVD risk found that, overall, hypertensive combination oral contraceptive users were found to be at higher risk of myocardial infarction (MI) and stroke than hypertensive non-combination oral contraceptive users, but the women who had their blood pressure measured before initiating combination oral contraceptives were at lower risk for ischemic stroke and MI than women who did not have such pre-initiation measurement (3). Because the risks of adverse events in pregnancy are increased in hypertensive women, ACOG recommends that non-smoking women with blood pressure well controlled by antihypertensive agents, under age 35 and otherwise healthy may try combination hormonal contraceptive methods with careful monitoring; if blood pressure remains controlled, use can be continued. Use of combination hormonal methods in women with severe (ie, uncontrolled) hypertension is contraindicated. Progestin-only methods, barrier methods and IUDs are appropriate options for women with either controlled or uncontrolled hypertension.
Disorders of lipoprotein metabolism can lead to the development of atherosclerosis, increasing the risk of cardiovascular disease (CVD), particularly myocardial infarction (MI). Although changes in lipoprotein metabolism with the use of exogenous steroids have been used as surrogate markers for CVD risk, the clinical significance of the effects of combination hormonal contraceptives on lipids is unknown. Lipid changes that have been observed during the use of hormonal contraceptives are not necessarily associated with future risk of MI or other CVD events (1, 5). Current low-dose combination hormonal contraceptives have minimal effects on the lipoprotein profile in normotensive, nonsmoking healthy women. There is no need to measure lipid levels prior to prescribing combination hormonal contraception unless a woman has known dyslipidemia, other CVD risks (eg, smoking, diabetes, obesity, hypertension), or history of pancreatitis. Sound clinical practice includes frequent monitoring of serum lipid levels until parameters are stabilized when low-dose combination hormonal contraceptives are used in women of any age with controlled dyslipidemia (5). Women of any age who have uncontrolled dyslipidemia (defined as low-density lipoprotein cholesterol >160 mg/dl, high-density lipoprotein cholesterol <35 mg/dl or triglycerides >250 mg/dl) and other risk factors for CVD or women with nephropathy or retinopathy should use a progestin only contraceptive. These methods include depot medroxyprogesterone acetate (DMPA), and etonogestrel implant, and IUDs do not have clinically meaningful effects on lipids and are appropriate for women with dyslipidemia.
The influence of exogenous estrogen on clotting mechanisms may synergistically further increase risk of thrombosis in women with thrombophilias; therefore, women with known inherited or acquired thrombophilias should not use estrogen-containing contraceptives. Women with familial thrombophilic syndromes, including factor V Leiden mutation, prothrombin G20210A mutation, and protein C, protein S, or antithrombin deficiency have an increased risk of venous thromboembolism during oral contraceptive use and also develop venous thromboembolism earlier during use than lower risk users (4). Progestin-only contraceptive methods, barrier methods and IUDs are appropriate options. Use of estrogen-containing contraceptives is also contraindicated in women with a personal history of thromboembolic disease, but progestin-only contraceptive methods, barrier methods and IUD are appropriate alternatives. However, ACOG states that individualized decisions may be made regarding use of combination hormonal methods in such women, if they are receiving anticoagulant therapy. This approach seems reasonable, as the small thrombophilic effect of estrogen is overcome by anticoagulant therapy. Routine testing for thrombophilic factors in asymptomatic women before contraceptive selection is not indicated, unless there is a strong family history of thrombophilia (eg, idiopathic VTE in a first-degree relative). Most women with thrombophilias will not develop VTE whether or not they use exogenous estrogen, and risk of VTE in pregnancy is higher for these women than that associated with combined hormonal contraception (4). Screening tests for coagulation disorders have poor positive predictive value for clinical events and may exclude many women who could safely benefit from use of hormonal contraception.
Mitral Valve Prolapse:
Asymptomatic mitral valve prolapse is not a contraindication to use of combination hormonal contraceptive methods. However, mitral valve regurgitation, arrhythmia, valve replacement, or the presence of other clinical symptoms precludes use of estrogen-containing methods, which could increase risk of VTE. Progestin-only methods, barrier methods and IUD are appropriate options.
The proportion of Americans who are obese (body mass index [BMI] of 30 or higher) has increased to 30%. Obesity may impair efficacy of combination oral and transdermal contraceptives. Among over-weight women, higher pregnancy rates have not been observed with use of the 150-mg intramuscular or 106-mg subcutaneous formulation of depot medroxyprogesterone acetate (DMPA). Use of oral contraceptives and obesity represent independent risk for VTE. Accordingly, consideration should be given to progestin-only and intrauterine methods when counseling obese women regarding contraceptive choices. In helping overweight women make sound contraceptive choices, practitioners should incorporate the above observations into discussions with patients. Because obese women experience an elevated risk for dysfunctional uterine bleeding and endometrial neoplasia, use of levonorgestrel intrauterine system may represent a particularly sound choice for obese women (5). Data are conflicting regarding whether obesity may decrease efficacy of some combination hormonal contraceptives. One study of combination hormonal contraceptive use and one of transdermal patch use have found somewhat higher pregnancy rates in overweight and obese women. However, in a study of a combination oral contraception containing ethinyl estradiol (EE) 25 mcg norgestimate, no significant differences in pregnancy rates were observed between women in the lowest weight decile (86 to 113.5 pounds) and the highest weight decile (175 to 240 pounds) (12). Therefore it appears that the contraceptive efficacy of combination hormonal methods is sufficiently high in overweight women, and those motivated to use these methods should not be excluded from doing so. However, these obese women should be made aware that obesity, age and use of estrogen-containing contraceptives are independent risk factors for VTE.
Temporary or Prolonged Immobilization:
Use of oral contraceptives at the time of arthroscopic surgery has been observed to increase VTE risk. Estrogen-containing methods should be discontinued 1 month prior to elective surgery associated with an increased VTE risk, and not restarted until 1 month post-surgery, to avoid further increasing perioperative risk of thrombosis. Although there are no data to support the recommendation, progestin-only contraceptive methods or barrier methods or IUD are appropriate for use in women who are paraplegic or otherwise immobilized by disease or injury. Because of low perioperative risk of VTE, it currently is not considered necessary to discontinue combination contraceptives before laparoscopic tubal sterilization or other brief surgical procedures not known to be associated with an elevated VTE risk (5).
Use of combination hormonal contraception is contraindicated in women with migraine headaches accompanied by aura (ie, focal neurological symptoms). Many studies of combination oral contraceptive use, stroke risk, and migraines do not distinguish migraine with aura from migraine without aura; therefore, there is still a concern as to whether all patients with migraine have an increased risk of stroke with combination pills (1, 3). ACOG guidelines state that combination hormonal methods may be used by women with migraine headaches who do not have focal neurologic symptoms, do not smoke, are otherwise healthy, and are younger than age 35. Progestin-only methods are appropriate options for women with migraine with aura who have no other risk factors for stroke (eg, smoking, hypertension). IUDs may be used by women with migraine with or without aura. Barrier methods are preferred in migraine patients with aura.
Women with Seizure Disorders:
Anticonvulsants that induce hepatic enzymes can decrease serum concentrations of the estrogen or progestin component of oral contraceptives, or both. This effect has been observed with phenobarbital, phenytoin, carbamazepine, oxcarbazepine, felbamate, and to a lesser extent, topiramte. Therapeutic doses of vigabatrin do not induce hepatic enzymes (5). Many studies have demonstrated reduced serum levels of oral contraceptive steroids during anticonvulsant use, and many of them demonstrated associated breakthrough bleeding, investigators did not observe ovulation or accidental pregnancy during anticoagulant use. In contrast to above anticonvulsants, use of valproic acid, gabapentin, tiagabine, levetiracetam, and zonisamide does not appear to decrease serum levels of contraceptive steroids in women using combination oral contraceptives. Although no formal pharmacokinetic data are available, use of ethosuximide, which does not have enzyme-inducing properties, is not thought to have an impact on steroid levels in oral contraceptive users. Practitioners should be aware; however, that studies of gabapentin, lamotrigine, and tiagabine were done using anticonvulsant does lower than those used in clinical practice. Combination hormonal methods are appropriate for use in women with seizure disorders whether or not they are taking enzyme-inducing anticonvulsants or other anticonvulsants. The large Oxford-Family Planning Association contraceptive cohort study found no evidence that combination hormonal methods increase the frequency of epileptic seizures (7). Although some authorities recommend using 50-mcg estrogen combination oral contraceptives in women taking enzyme-inducers, ACOG states that there are no published data supporting this recommendation. Because progestin-only oral contraceptives are very low-dose contraceptives, their use would not appear prudent in women using enzyme inducers. Product labeling for the etonogestrel implant indicates that this method is not appropriate for women chronically taking enzyme-inducing drugs. DMPA is a high-dose progestin-only contraceptive and concomitant use of enzyme inducers has not been found to increase risk of pregnancy in women using this method. In addition, use of DMPA has been found to reduce seizure frequency in women with seizure disorder.
Systemic Lupus Erythematosus (SLE):
Although effective contraception is important for women with lupus, concerns about increasing disease activity and thrombosis have resulted in clinicians rarely prescribing combination estrogen-progestin oral contraceptives to women with this disease. The findings of two large randomized trials support the safety of combination oral contraceptive use in women with inactive or stable SLE who do not have moderate or high levels of anticardiolipin antibodies (6). ACOG recommends that estrogen-containing contraceptives not be used by women with SLE and a history of vascular disease, nephritis, or presence of antiphospholipid antibodies. Progestin-only methods, barrier methods and IUD are appropriate methods for these women.
Multiple Sclerosis (MS):
Data from the Nurses' Health Study cohorts indicate that use of oral contraceptives is not associated with risk of development of MS. A recent questionnaire study of MS symptoms in pregnancy, postpartum, and combination oral contraceptive use found no change in symptoms, among 64% of pregnant women, 59% of postpartum women, and 67% of combination oral contraceptive users. No combination oral contraceptive users reported worsening of symptoms, and 13% reported symptom improvement, suggesting that there is no progression and possible amelioration of MS during combination hormonal contraceptive use (9). Progestin-only contraceptive methods, barrier methods and IUDs are also appropriate options for women with MS.
Sickle Cell Disease:
In individuals with sickle cell disease, abnormal hemoglobin precipitates becomes rigid when subjected to oxygen deprivation. Vasoocclusive episodes in those with sickle cell disease, however, differ from intravascular thrombosis. Two controlled studies have assessed the use of DMPA in women with sickle cell disease. Both of these found that use of DMPA reduced the incidence of painful crises. Accordingly, DMPA may be a particularly appropriate contraceptive for women with sickle cell disease (5). No well-controlled study has assessed whether VTE risk in oral contraceptive users with sickle cell disease is higher than in other combination oral contraceptive users. Cross-sectional studies in women with sickle cell disease have observed no differences in markers of platelet activation, thrombin generation, fibrinolysis, or red cell deformability between users of combination oral contraceptives, progestin-only methods, and non-users of hormonal contraception. On the basis of these observations as well as studies of pregnant women with sickle cell disease, small observational studies of women with sickle cell disease who use combination oral contraceptives, and theoretical considerations, the consensus is that pregnancy carries a greater risk than does combination oral contraceptive use. Progestin-only, barrier methods and IUDs are appropriate contraceptive options for women with sickle cell disease.
Depression and Bipolar Disorder:
In an analysis of data from 17 placebo-controlled trials of women receiving the antidepressant fluoxetine, there was no clinical evidence that concomitant use of combination oral contraceptives and fluoxetine affects the safety or efficacy to either agent (10). In a prospective cohort study, depressive symptom scores improved slightly from baseline (method initiation) after 1 year of DMPA use, suggesting that DMPA should not exacerbate symptoms in women with pre-existing depression. Some women with psychiatric disorders may have difficulty in adhering to daily, weekly, or monthly contraceptive regimens, so IUD and implantable contraception may be advantageous alternatives. Women with bipolar disorders are sometimes treated with antiepileptic drugs, so the cautions discussed above also apply to some women with bipolar disorder. IUDs may be appropriate options for women using antiepileptic drugs to treat bipolar disorder.
Benign and Malignant Breast Diseases:
Women with fibroadenoma, benign breast disease with epithelial hyperplasia with or without atypia, or a family history of breast cancer have an increased risk of breast cancer. The meta-analysis of the 54 studies found that 10 or more years after discontinuing oral contraceptive use, risk of breast cancer was identical in former and never users of oral contraceptives (11). More recently, the Women's CARE study, a large U.S. population-based case-control study conducted by the National Institutes of Health, found no increased risk of breast cancer with current or past oral contraceptives. No significant differences in overall results were noted for time since last oral contraceptive use, duration of use, age at first use, age at last use, or family history of breast cancer. The Women's CARE study likewise found no increased risk of breast cancer to be associated with use of DMPA. A case-control study focused on cases of breast cancer diagnosed before age 40 years and concluded a substantial number of BRCA1 and BRCA2 mutation carrier (12). Compared with never using oral contraceptives, using current low-dose oral contraceptive formulations did not increase the risk of breast cancer in carriers of BRCA1 or BRCA2 mutations. A history of benign breast disease or a positive family history of breast cancer (including BRCA1 or BRCA2 mutations) should not be regarded as contraindications to oral contraceptive use. The BRCA1 and BRCA2 mutations are associated with a 45% and 25% lifetime risk, respectively, for epithelial ovarian cancer. Because oral contraceptive use reduces ovarian cancer risk in BRCA1 and BRCA2 carriers, as it does in non-carriers, use of oral contraceptives offer important benefits for women with BRCA1 and BRCA2 mutations.
Cancer and Hormonal Contraception:
Modern contraceptives have undergone extensive study over the past 50 years, providing a huge body of evidence exploring the possible associations between contraceptive use and the risks of developing various cancers. No contraceptive method has been found to be associated with a definitive increased risk of any malignancy. Many methods are associated with reduced risks of certain cancers, either during use, for periods of time following discontinuation, and/or lifelong. Some subgroups of women who have a positive family history for cancer or specific genetic mutations or ethnicity that predispose them to various cancers are concerned about an adverse impact of hormonal contraceptives on their risk for developing cancer, but there is no conclusive evidence that contraceptive use further increases the background risks of cancer in these women. Regardless of contraceptive use, the probability of developing any cancer usually increases with increasing age. However, among reproductive-age women, the risk of developing cancer are extremely slight (13). The studies discussed in the following sections have mostly examined oral contraceptives. Although robust epidemiologic data are not yet available for other contraception delivery regimens, it is biologically plausible to assume that other combination hormonal methods (transdermal contraceptive patch, vaginal ring) are likely to have similar associations.
Ovarian Cancer: According to the Royal College of General Practitioner's (RCGP) study (13), lifetime risk of ovarian cancer is reduced by >40% with oral contraceptive use. A 2008 reanalysis of data from 45 epidemiologic studies found that, overall, oral contraceptive ever-use was associated with a substantial reduction in the risk of ovarian cancer compared with oral contraceptive never-use, with risk reduction evident for as little as 1 year of oral contraceptive use. This risk was further reduced with increasing duration of oral contraceptive use, by about 20% for each 5 years of use. The researchers involved in this study estimated that 30,000 cases of ovarian cancer are prevented each year worldwide because of oral contraceptive use. Nearly all studies have demonstrated that the use of oral contraceptives reduces the risk of ovarian cancer in women with family histories of ovarian and/or breast cancer, and in those with BRCA mutations, to degrees similar to the protection seen in women without such background risks.
Endometrial Cancer: During the past 4 decades, studies have consistently demonstrated substantial risk reductions in endometrial cancer with oral contraceptive use (14). According to the RCGP, oral contraceptive use reduced lifetime risk of endometrial cancer by >40% compared with oral contraceptive nonuse. The degree of protection is directly related to duration of oral contraceptive use, beginning after 1 year of use and persisting for at least 15 to 20 years after discontinuation (13). This long term reduction in the risk of endometrial cancer is a major benefit of oral contraceptive use. A World Health Organization study found that ever-use of DMPA, and protection appeared to persist for at least 8 years after discontinuation of the method.
Cervical Cancer: Within the past 10 years, human papillomavirus (HPV) infection has been conclusively identified as present in essentially all cases (99.7%) of epithelial cervical cancers. Both the RCGP and a meta-analysis of 24 epidemiologic studies reported a slight increased risk of cervical cancer with increasing duration of oral contraceptive use compared with oral contraceptive non-use. Cervical cancer is caused by HPV -- a sexually transmitted infection, and consistent condom use is protective against many sexually transmitted diseases, including HPV. However, women using oral contraceptives for contraception are more likely to engage in sexual behavior (more sexual activity and greater number of sexual partners); they are less likely than women not using oral contraceptives to use condoms and may thus be more likely to be exposed to HPV. According to the 2002 National Survey of Family Growth, whereas 24.2% of women using contraception, aged 15 to 44 years, used condoms alone or in combination with another contraceptive method, only 4.2% of these women used oral contraception in combination with condoms (15). Clinicians are reminded of the importance of regular cervical cytologic screening for all women, regardless of their use of contraception or whether they have received an HPV vaccine. However, cervical cancer screening is not necessary prior to prescribing contraception. Women and clinicians should be assured that concern about cervical cancer is not a reason to avoid the use of combination hormonal contraception. The frequency with which teenagers report sexual activity and the high unintended pregnancy rate in this age group makes counseling regarding effective contraception essential. Additionally, practitioners are encouraged to take the opportunity to discuss the availability of the human papillomavirus (HPV) vaccine with adolescents. In 2007, adolescents were designated as a special population, given the frequency with which they acquire and clear mild HPV-related cervical dysplasia (19).
Colorectal Cancer: Studies of oral contraceptive use and the risk of colorectal cancer have reported varying results, with some finding no association and other findings decreased risk (16).
Hormonal Contraceptive Options for Postpartum and Lactating Women:
Postpartum women remain in a hypercoagulable state for weeks after childbirth. Product labeling for combination oral contraceptives advises deferring use until 4 weeks postpartum in non-breastfeeding women. Because progestin-only oral contraceptives and DMPA do not contain estrogen, these methods may be safely initiated in immediate postpartum. Traditionally, combination oral contraceptives have not been recommended as the first choice for breastfeeding women because of concerns that the estrogenic component of combination oral contraceptives can reduce the volume of milk production and the caloric and mineral content of breast milk in lactating women. However, use of combination oral contraceptives by well-nourished breastfeeding women does not appear to result in infant development problems. Use of combination hormonal contraceptives can be considered once milk flow is well established (11). Progestin-only pills and DMPA do not impair lactation, and in fact may increase the quality and duration of lactation. Product labeling for progestin-only pills suggests that fully breastfeeding women begin tablets 6 weeks postpartum and advise partially breastfeeding women to begin at 3 weeks. When initiated in immediate postpartum, use of DMPA does not adversely lactation or infant development (17). Given the lack of procoagulation effect and the safety in breastfeeding women with DMPA and progestin-only pills, their use at 6 weeks postpartum in lactating women and in immediate postpartum period in non-lactating women appears reasonable.
Premenstrual Dysphoric Disorder (PMDD):
Premenstrual disorders negatively affect millions of U.S. women. The premenstrual disorder at the most severe end of the spectrum is premenstrual dysphoric disorder (PMDD). The U. S. Food and Drug Administration (FDA) has approved 4 agents for the treatment of PMDD: 3 antidepressants (i.e., selective serotonin reuptake inhibitors [SSRIs]) and 1 low-dose combination oral contraceptive that contains the progestin drospirenone and is administered using a regimen of 24 days of active pills in a 28-day cycle (drospirenone/20EE-24/4 [YAZ®]). Drospirenone is unique among progestins used in combination oral contraceptives in that it has both antimineralocorticoid and antiandrogenic activities. Two pivotal studies have shown drospirenone/20EE-24/4 to be effective in treating mood, physical and behavioral symptoms of PMDD and symptoms specifically associated with food, water retention and negative interpersonal relationships (18). SSRIs are effective for mood and behavioral symptoms; however, they are likely to be less effective for physical symptoms or may require an increased dose. The side effects of SSRIs may limit their use in some women. Drospirenone/20EE-24/4 has been shown to be effective in treating mood, physical and behavioral symptoms of PMDD.
Women of all ages who are seeking a birth control method indicate that pregnancy prevention, ease and convenience of use are important factors affecting their choice. In women with many medical conditions, pregnancy increases risks of disease exacerbation, co-morbidity, and mortality. Such heightened risks underscore the importance of effective contraception to help women with medical conditions avoid pregnancy or delay it until optimal therapeutic control of the underlying conditions avoid pregnancy or delay it until optimal therapeutic control of the underlying condition is achieved. Fortunately, a variety of highly effective contraceptive methods with differing characteristics are available. Healthcare provider's familiarity with the benefit/risk profiles of these methods can enhance appropriate selection of contraception for women with various medical conditions. Perimenopausal women may benefit from a positive effect on bone mineral density and a reduction in vasomotor symptoms offered by combination oral contraceptives. In addition, the reduced risk of endometrial and ovarian cancers associated with oral contraceptive use is of particular importance to older women of reproductive age. The key to helping patients successfully use contraception is to discuss individual preferences and to offer as many appropriate options as possible.
Venous thromboembolism (VTE) is a rare event in reproductive-age women, ranging from 1 to 10 events per 10,000 woman-years, depending on the population under investigation. The risk of VTE is substantially increased in women with known risk factors, including inherited thrombophilias, obesity, and diabetes. In women without known VTE risk factors, use of hormonal contraception, and presumably that of other combination hormonal contraception methods, is generally accepted to increase risk of VTE 3-fold. However, the absolute risk remains low (3 to 30 events per 10,000 woman-years). The excess risk of VTE attributable to use of combination hormonal contraception is substantially less than that attributable to pregnancy. Counseling women regarding the safety of contraceptives should focus on absolute rather than relative risk. The preponderance of evidence shows that no currently available hormonal contraceptive method increases the risk of any cancer; all methods are associated with some potential decreased risks or no effect on existing risk compared with non-use. Overall lifetime risk of developing any cancer is reduced by 12% with the use of oral contraceptives. Women should be reassured by this information during contraception counseling.
The series on Contraception is funded by WHEC Initiative for the Global Health. We also thank the reviewers for their useful comments towards improving the Practice Bulletin.