The effects of age,body mass index,smoking and general health on the risk of venous thromboembolism in users of combined oral contraceptives

Objectives To investigate the factors associated with idiopathic venous thromboembolism in combined oral contraceptive users and to estimate the crude and age-specific incidence rates of idiopathic venous thromboembolism among this population.

Methods The UK MediPlus Database and the General Practice Research Database were searched to identify women with evidence of venous thromboembolism while exposed to combined oral contraceptives. Cohort and nested case-control studies were carried out using the same methodology on both databases. We conducted a meta-analysis using the individual data for the cases and controls from the two case-control studies to identify factors associated with idiopathic venous thromboembolism in women using combined oral contraceptives.

Results The incidence rate of idiopathic venous thromboembolism among oral contraceptive users was 39.4 per 100 000 exposed woman-years. The age-specific incidence rates were found to rise sharply after the age of 39 years. Factors identified as being significantly associated with idiopathic venous thromboembolism in women using combined oral contraceptives were: body mass index of 25 kg/m² and over, the association rising dramatically in women with a body mass index of 35 kg/m² or more; smoking; general ill health; and asthma.

Conclusion We believe that, before prescribing combined oral contraceptives, the venous as well as the arterial factors need to be considered and, in addition, age, obesity and smoking are all relevant when assessing an individual patient's risk.     

Oral contraceptives increase deep venous thrombosis in smoking women

There is consistent evidence that the use of oral contraceptives and is associated with increased risk of deep vein thrombosis. The study objective was to assess age specific incidence of deep venous thrombosis and pulmonary embolism in women 20 to 50 years of age associated with the use of oral contraceptives, and smoking habit. A case-control study of vein thrombosis was conducted in National Heart Hospital in Sofia. The study consists of studies for vascular events (peripheral vascular disease) during hormonal therapy. We found that cigarette smoking aggravates venous thromboembolism and pulmonary embolism the in women using oral contraceptives, v. The effect of smoking alone on venous tromboembolism was not found significant. Most probably different factors that increase the incidence of vascular narrowing or occlusion might explain the association between deep venous thrombosis, complicated pulmonary thromboembolism oral contraceptives use and smoking in women in pre-menopausal age.     

Are factor V Leiden carriers who use oral contraceptives at extreme risk for venous thromboembolism?

BACKGROUND: Major concern was raised by an earlier study regarding oral contraceptive use in women with the factor V Leiden mutation. A more than 30-fold increase in relative risk for venous thromboembolism was reported; for homozygotes, the relative risk was as much as 100-fold or more. OBJECTIVE: To replicate the reported risk estimates with a new population-based case-control study. METHODS: Eighty women with a diagnosis of venous thromboembolism were consecutively identified and compared with population-based controls (n = 406). Factor V Leiden mutation was identified by genotype analysis. The evaluation was performed with conditional logistic regression (matched for 5-year age group). RESULTS: Matched, adjusted odds ratios (OR) for idiopathic venous thromboembolism in women without and with the factor V Leiden mutation who used oral contraceptives were 4.1 (95% confidence interval (CI) 2.1-7.8) and 10.2 (95% CI 1.2-88.4), respectively. The adjusted OR for factor V Leiden carriers was 2.0 (95% CI 1.0-4.4). The OR for women with the factor V Leiden mutation and oral contraceptive use versus no factor V Leiden mutation and no oral contraceptive use was 10.2 (95% CI 3.8-27.6). CONCLUSION: The results confirm the increased relative risk of idiopathic venous thromboembolism for users of oral contraceptives and factor V Leiden carriers. However, we suspect that the true risk for women who are factor V Leiden carriers may be increased two- to four-fold rather than seven-fold or more, and that the risk for the combination of factor V Leiden and oral contraceptive use may be increased in the order often- to 15-fold rather than over 30-fold.     

Oral contraceptives and thromboembolism: A reassessment

The relationship between oral contraceptive usage and thromboembolism is controversial. Since thromboembolism is often undiagnosed, both clinically and at routine autopsy, most epidemiologic analyses rest on a very uncertain factual base. There are increases in blood coagulation factors in oral contraceptive users similar to, but less than, those seen in pregnancy, which isnot associated with increased thromboembolism. Hematologists emphasize that these changes do not define a “hypercoagulable” state, and they do not define or predict the occurrence of thrombosis. Intrinsic vascular wall changes, unrelated to drug use, may play a role in sporadic cases of thromboembolism. When the incidence of thromboembolism in very large Phase III trials of conventional oral contraceptives is compared to that in other populations (patients admitted to the hospital, women who visit a physician, pregnant women, or users of nonestrogenic oral contraceptives), no difference is seen. Epidemiologic studies by the “case-control” (“trohoc”) method consistently show an increased “relative risk” associated with oral contraceptive use in subjects with “idiopathic” thromboembolism but no increased risk in thromboembolism patients as a whole or in those with predisposing factors. This retrospective epidemiologic technique, its particular applications, and the inferences drawn are open to serious criticism, as are studies claiming a relationship between estrogen dose and thromboembolism incidence. An Australian prospective survey found no increased risk among users, and a large British study which initially reported an increased risk is currently undergoing recalculation. The only controlled clinical experiment (with random assignment of subjects to vaginal versus high-estrogen contraceptives) showed no increased incidence in the drug-treated group. Statistical associations derived from “trohoc” studies do not establish causal relationships; moreover, their risk estimates are in conflict with the findings of large Phase III clinical surveys including subjects using estrogen-free contraceptives, with at least one prospective clinical survey, and with a randomized, controlled clinical trial. The data relating estrogen dosage to thromboembolism incidence are ambiguous, at best. Thus, the claim of a causal relationship between oral contraceptive steroids and thromboembolism does not appear to be firmly founded, and the belief that predisposing factors increase the risk to contraceptive users is equally insubstantial.     

Oral progestogen-only contraceptives and cardiovascular risk: results from the Transnational Study on Oral Contraceptives and the Health of Young Women.

BACKGROUND: The risk of cardiovascular disease associated with progestogen-only pills has rarely been studied so far. METHODS: In the Transnational case-control study we were looking for a potential cardiovascular disease risk with oral progestogen-only pills in women aged 16-44 years. A total of 1058 cases of myocardial infarction, thromboembolic cerebrovascular accident or venous thromboembolism, and 3808 controls unaffected by these diseases, were enrolled. The group of women who had either used oral progestogen-only pills or no oral contraceptives included 394 cardiovascular disease cases (123 cases of myocardial infarction, 90 cases of thromboembolic cerebrovascular accident and 181 cases of venous thromboembolism) and 2366 controls. RESULTS: The adjusted (matched) odds ratio (OR) for all cardiovascular diseases combined for women using progestogen-only pills compared with non-users of oral contraceptives was 0.84 (95% confidence interval (CI), 0.45-1.58). The adjusted ORs for myocardial infarction, thromboembolic cerebrovascular accidents and venous thromboembolism for users of progestogen-only pills were 0.94 (95% CI, 0.31-2.91), 1.60 (95% CI, 0.24-0.72) and 0.68 (95% CI, 0.28-1.66), respectively. Hence, there was no significant increase in cardiovascular disease risk associated with progestogen-only pill use. The association between cardiovascular disease and established risk factors (smoking and hypertension) was confirmed. CONCLUSION: Although limited by the small number of exposed cases, our data suggest that there is no convincing evidence for an increased risk of cardiovascular disease associated with progestogen-only pill use.     

Venous thromboembolism and oral contraceptive use: a methodological study of diagnostic suspicion and referral bias.

BACKGROUND: In studies of oral contraceptive oral contraceptive use and risk of venous thromboembolism, bias related to heightened diagnostic suspicion and preferential referral of oral contraceptive users has been an issue. The aim of our study was to determine the presence and potential impact of diagnostic suspicion and referral bias. METHODS: We conducted a case/non-case study in 21 regional study centers in Germany and, in parallel, a conventional case-control study using the same cases but randomly selected population controls from the same areas. Women with symptoms compatible with venous thromboembolism were included in the study between 1994 and 1999, and classified as cases or non-cases (first reference group) according to the diagnostic work-up (case/non-case study). A second reference group consisted ofpopulation controls (conventional case-control study as an internal comparison for the case/non-case study): 606 cases, 462 non-cases and 2942 population controls aged 15-49 years. Adjusted unconditional regression analyses were performed. RESULTS: Adjusted odds ratios for venous thromboembolism in oral contraceptive users were systematically higher in the classical case-control study compared to the case/non-case approach (using the same cases) across all subgroup analyses (e.g. for idiopathic cases, the odds ratio was 67% higher in the case-control study: 4.33 (95% confidence interval (CI) 3.27-5.74) versus 2.60 (95% CI 1.75-3.88)). We found a significantly increasing trend of oral contraceptive use in four categories of increasingly sophisticated diagnostic tests that were applied to 1067 women with a suspicion of venous thromboembolism, irrespective of the outcome. Stratified analysis showed the diagnostic level to be a confounder. CONCLUSION: In our population-based study with the possibility of internal comparison, we found clear evidence that diagnostic suspicion and referral bias does play an important role in case-control studies of venous thromboembolism risk among oral contraceptive users. This underlines the importance of making an effort to avoid this bias when designing a new study.     

Contraceptive choices in women with coagulation disorders

When compared with older reports on the thromboembolic effects of high-dose oral contraceptives, new studies with low-dose oral contraceptives have a significantly reduced risk of thromboembolism. In the absence of risk factors such as smoking or inherited disorders predisposing to thrombosis, the modern low-dose oral contraceptive (< 50 μg of estrogen) is a safe and effective choice for contraception in women without symptoms who have family histories of sporadic thromboembolism. An intrauterine device or some form of barrier method is recommended for women who have a personal history of venous thrombus disease. The low-dose oral contraceptive may be a good choice in women taking oral anticoagulants because of the risk of teratogenic effects of anticoagulants and the risks of intraperitoneal bleeding associated with ovulation. In addition, oral contraceptives help diminish the excessive menstrual bleeding often seen in these women. (Am J Obstet Gynecol 1993;168:1990-3.)     

Venous thromboembolism in relation to oral contraceptive use

The relation of the risk of venous thromboembolism to the use of oral contraceptives was assessed in a hospital-based study of 61 women suffering from a first episode of idiopathic deep vein thrombosis or pulmonary embolism (cases) and 1278 women admitted for trauma or respiratory infections (controls). Twenty (33%) of the cases and 121 (9%) of the controls had used oral contraceptives within the previous month, yielding an age-adjusted relative risk estimate of 8.1 (95% confidence interval 3.7 to 18) for recent users relative to never-users. For women using oral contraceptives containing less than 50 micrograms estrogen, the relative risk estimate was 11 (3.7 to 22); for preparations with 50 micrograms estrogen, it was 5.5 (2.1 to 15); and for preparations with more than 50 micrograms estrogen, it was 11 (3.9 to 30). Past use of oral contraceptives was not associated with an increased risk. The data suggest that the risk of venous thromboembolism is increased for recent oral contraceptive users relative to nonusers, even if women use oral contraceptives containing low doses of estrogen. Confidence intervals were wide, however, so that a reduction in the risk for users of lower dose formulations relative to users of higher dose formulations cannot be ruled out. Selection bias, if present, would have resulted in overestimation of the relative risk, but should not have distorted the comparisons according to dosage.     

Venous thromboembolism and oral contraceptive use: a methodological study of diagnostic suspicion and referral bias

Background In studies of oral contraceptive oral contraceptive use and risk of venous thromboembolism, bias related to heightened diagnostic suspicion and preferential referral of oral contraceptive users has been an issue. The aim of our study was to determine the presence and potential impact of diagnostic suspicion and referral bias.

Methods We conducted a case/non-case study in 21 regional study centers in Germany and, in parallel, a conventional case-control study using the same cases but randomly selected population controls from the same areas. Women with symptoms compatible with venous thromboembolism were included in the study between 1994 and 1999, and classified as cases or non-cases (first reference group) according to the diagnostic work-up (case/non-case study). A second reference group consisted of population controls (conventional case-control study as an internal comparison for the case/non-case study): 606 cases, 462 non-cases and 2942 population controls aged 15–49 years. Adjusted unconditional regression analyses were performed.

Results Adjusted odds ratios for venous thromboembolism in oral contraceptive users were systematically higher in the classical case-control study compared to the case/non-case approach (using the same cases) across all subgroup analyses (e.g. for idiopathic cases, the odds ratio was 67% higher in the case-control study: 4.33 (95% confidence interval (CI) 3.27–5.74) versus 2.60 (95% CI 1.75–3.88)). We found a significantly increasing trend of oral contraceptive use in four categories of increasingly sophisticated diagnostic tests that were applied to 1067 women with a suspicion of venous thromboembolism, irrespective of the outcome. Stratified analysis showed the diagnostic level to be a confounder.

Conclusion In our population-based study with the possibility of internal comparison, we found clear evidence that diagnostic suspicion and referral bias does play an important role in case-control studies of venous thromboembolism risk among oral contraceptive users. This underlines the importance of making an effort to avoid this bias when designing a new study.     

Combined hormonal contraceptives and venous thromboembolism: putting the risks into perspective

To date, 13 studies have provided data on the risk of venous thromboembolism associated with combined oral contraceptives containing drospirenone or the norelgestromin-containing contraceptive patch. The studies varied in their conclusions about whether these methods are associated with higher risks than combined oral contraceptives containing other progestins: the primary reported measures of association (adjusted odds ratios, incidence rate ratios, or hazard ratios) ranged from 0.9 to 3.3. All of the studies had weaknesses in population selection, data validity or completeness, or analysis that may have led to biased or spurious findings. Venous thromboembolism is rare; if the contraceptive methods of interest do confer a higher risk of thromboembolism, only an additional 5-10 per 10,000 users per year would be affected. The important message for patients, clinicians, and policy makers is that the benefits of all contraceptive methods markedly outweigh their risks, primarily because they prevent pregnancy, an inherently hazardous condition. Product labels for hormonal contraceptives should emphasize their substantial health benefits and established safety.     

Oral contraceptives, thrombosis and haemostasis

The use of oral contraceptives is a well-established acquired risk factor for venous thrombosis. In 1995, a number of epidemiological studies were published which suggested that women who use third generation oral contraceptives that contain desogestrel or gestodene as progestagen are exposed to a two- to threefold higher risk for venous thrombosis than women using second generation oral contraceptives which contain levonorgestrel. In this paper, the effects of oral contraceptives on the haemostatic system are discussed. It appears that plasma from oral contraceptive users is resistant to the anticoagulant action of activated protein C (APC). This phenomenon, called acquired APC resistance, is more pronounced in users of desogestrel or gestodene-containing oral contraceptives than in women who use oral contraceptive pills with levonorgestrel. On the basis of these observations, it was proposed that acquired APC resistance may be the mechanistic basis of the increased risk for venous thrombosis during oral contraceptive use and for the further increased thrombotic risk of third generation oral contraceptive users. Furthermore, the results of a recent cross-over study are discussed. This study indicated that a large number of other haemostatic parameters were changed during oral contraceptive use. Some of these changes were more pronounced on desogestrel-containing oral contraceptives. The cross-over study also showed that the increased fibrinolytic activity during OC use is counterbalanced by an enhanced activity of thrombin-activatable fibrinolysis inhibitor (TAFI), a protein that participates in the inhibition of fibrinolysis.     

Oral contraception: safety issues re-examined.

Oral contraceptives are highly effective contraceptive agents that are used throughout the world. However, misperceptions about the safety of oral contraceptives as well as a relative lack of information concerning their numerous and important noncontraceptive benefits may limit their use and place women at increased risk for unintended pregnancy. Safety issues concerning the use of oral contraceptives have largely been laid to rest; indeed, except for a slight increased risk of venous thromboembolism in combination oral contraceptive users, conventional oral contraceptive use is not associated with an increased risk for cardiovascular events. In addition, fears regarding breast cancer development in OC users have been unsubstantiated by the plethora of available data. Clinicians must provide accurate and empathetic counseling concerning the safety and applicability of oral contraceptives and other pregnancy prevention methods.     

Cardiovascular issues with oral contraceptives: evidenced-based medicine

Recent studies of current oral contraceptives indicate that the risk of cardiovascular sequelae is low in young (age 20-24 years) reproductive-aged women. Venous thromboembolism remains the one event that occurs in users independent of the presence of risk factors. However, the attributable risk is small, in the range of 7 to 18 events per 100,000 women annually. This risk is proportional to estrogen dose until the level of 30-35 microg is reached; type of progestin may also influence risk, though recent studies are controversial. Modifiable risk factors for venous thromboembolism include the presence of hemostatic disorders, especially factor V Leiden, and perhaps obesity. Stroke is even more uncommon, with an attributable risk of about 1.5 events per 100,000 women annually. Cigarette smoking and hypertension are modifiable risk factors for both ischemic and hemorrhagic stroke; use of preparations with 50 microg of estrogen or higher and migraine headaches are risk factors for ischemic stroke. Eliminating risk factors among users substantially reduces the risk of ischemic stroke and virtually eliminates the risk of hemorrhagic stroke. Myocardial infarction is rare among young women, occurring at a rate of about 0.2 event per 100,000 women annually. Oral contraceptive users who are non-smoking and normotensive do not have an increased risk of myocardial infarction. However, the presence of these risk factors along with age acts synergistically to increase the risk among oral contraceptive users.     

Interleukin-6 and antiphospholipid antibodies in women with contraceptive-related thromboembolic disease

OBJECTIVE: The aim of this study was to explore the possible (joint) contributing role of interleukin-6 (IL-6) and antiphospholipid antibodies to the occurrence of the venous thromboembolism in women using oral contraceptives. METHODS: Interleukin-6 and antiphospholipid antibodies (anti-beta2-glycoprotein I antibody-immunoglobulin M [IgM], G [IgG], and A [IgA]; anticardiolipin-IgM and IgG; antiphosphatidylserine-IgM and IgG) were measured in 30 women (median age 41, range 28-49 years) in the stable period (on average 3.5 years) after first venous thromboembolism. Sixteen patients used oral contraceptives during the episode of venous thromboembolism (oral contraceptives group), whereas 14 patients did not (non-oral contraceptives group). Thirty-seven age-matched, healthy women served as controls RESULTS: Compared with controls, the oral contraceptives group had elevated IL-6 (median interquartile range 2.3 [1.1-4.3] versus 1.4 [0-2.0] pg/mL, P <.05). The oral contraceptives group had elevated anti-beta2-glycoprotein I antibody-IgM in comparison with both the non-oral contraceptives group (median interquartile range 47.5 [2.0-77.0] versus 29.50 [11.00-45.50] OD(450), P <.06) and controls (47.5 [2.0-77.0] versus 17.5 [3.5-30.0] OD(450), P <.001). Interleukin-6 level in the non-oral contraceptives group was related to obesity, whereas such a relation was not found in the oral contraceptives group, suggesting the presence of another factor (oral contraceptive use), which stimulates IL-6 production. Of particular interest is our finding that elevated IL-6 levels correlated significantly positively with elevated anti-beta2-glycoprotein I antibody-IgG in patients who were users of oral contraceptives (but not overweight, n = 10) (r = 0.56, P <.05) CONCLUSION: The results suggest a new hypothesis that, in susceptible women, use of oral contraceptives induces production of IL-6, which stimulates production of anti-beta2-glycoprotein I. Thus, the prothrombotic profile is aggravated and could facilitate occurrence of venous thromboembolism. This remains to be elucidated in further studies.     

Effects of third-generation oral contraceptives on high-sensitivity C-reactive protein and homocysteine in young women

OBJECTIVE: To evaluate the effect of third-generation oral contraceptives on high-sensitivity C-reactive protein (CRP), homocysteine, and lipids levels in a population of young, fertile, nonobese women. METHODS: Blood markers were evaluated in 277 healthy white women (mean age 23 years and mean body-mass index 21 kg/m(2)). Seventy-seven oral contraceptive users were compared with 200 non-oral contraceptive users. Progressive cutoffs of high-sensitivity CRP and homocysteine levels were examined. RESULTS: Levels of high-sensitivity CRP posing a high risk of cardiovascular disease (3.0 to less than 10.0 mg/L) were found in 27.3% of oral contraceptive users and in 8.5% of non-oral contraceptive users (odds ratio 4.04; 95% confidence interval [CI] 1.99-8.18). Levels of high-sensitivity CRP at intermediate risk (1.0 to less than 3.0 mg/L) were found in 32.5% of oral contraceptive users and in 11.0% of non-oral contraceptive users (odds ratio 3.89; 95% CI 2.03-7.46). Notably, non-oral contraceptive users were 8.65 (95% CI 4.39-17.1) times as likely to demonstrate a protective level of high-sensitivity CRP (less than 0.5 mg/L) compared with oral contraceptive users. Oral contraceptive use increased serum triglycerides (P<.001) and total cholesterol P=.001); however, high-density lipoprotein, not low-density lipoprotein, contributed to this increase. A decreased ratio of low-density lipoprotein to high-density lipoprotein cholesterol was observed in oral contraceptive users compared with nonusers (P=.016). Oral contraceptive use did not affect homocysteine levels. CONCLUSION: Third-generation oral contraceptive use increases low-grade inflammatory status measured by high-sensitivity CRP concentrations. Alteration of inflammatory status in oral contraceptive users could affect the risk of venous thromboembolism, cardiovascular disease, and other oral contraceptive-associated adverse conditions in young women.     

The Royal College of General Practitioners' Oral Contraception Study: some recent observations

The Royal College of General Practitioners' Oral Contraception Study is a continuing cohort survey of the effects of oral contraceptives on the health of users. Neurotic depression is associated with the oestrogen content of combined oral contraceptives, but the risk is small in general, and there is no excess risk associated with oestrogen doses of 35 micrograms or less. It now appears likely that, in the long-term, oral contraceptives are not associated with any increased risk of gallbladder disease, although there is an acceleration of the disease in those women susceptible to it. The progestogen activity of combined oral contraceptives is associated with an increased risk of hypertension and arterial disease. Duration of use no longer seems to influence the occurrence of the latter. Cigarette smoking by oral contraceptive users is the predominant associated risk factor for the occurrence of arterial diseases. Non-smokers using low-progestogen-dose brands may safely use oral contraceptives, probably up to the age of 45 years. In the author's opinion, there is no convincing evidence that oral contraceptive use increases the risk of breast cancer. The evidence for an association with cervical cancer is firmer, but, if confirmed, is unlikely to affect more than one in 3000 users a year. Increased safety in the use of oral contraceptives in future is likely to be achieved through the use of tests which will allow the adjustment of dose to be made to each patient's particular requirements.     

Oral contraception, mechanical contraception, and carbohydrate and lipid metabolism: a two-year study.

The carbohydrate and lipid metabolism of 100 women using an oral contraceptive (0.5 mg norgestrel + 0.05 mg ethinyl estradiol) and of 96 women using mechanical contraceptives was monitored over a 2-year period. The women had been screened for factors known to adversely affect carbohydrate and lipid metabolism. Two-hour oral glucose tolerance tests were performed at 6-month intervals during the study; serum insulin was determined at the same intervals in half the women. Triglycerides, total cholesterol, free fatty acids, and body weight were also measured. The study showed no significant differences in lipid metabolism nor in weight gain between women using oral or mechanical contraceptives. After 6 months the fasting glucose of women using oral contraceptives was significantly decreased; at 120 minutes, glucose and insulin levels were significantly increased in comparison to women using mechanical contraceptives. A greater percentage of oral contraceptive users had borderline-abnormal oral glucose tolerance tests but the abnormalities did not persist in the same individuals during the study. The incidence of a pathological oral glucose tolerance with oral contraceptives was 1%.     

The influence of oral contraceptives on the risk of multiple sclerosis

Objective To examine the risk of multiple sclerosis in users of combined oral contraceptives.
Design Cohort study conducted between 1968 and 1996 using diagnostic data supplied by general practitioners
Setting General practices throughout the United Kingdom.
Population Royal College of General Practitioners' Oral Contraception Study cohort of initially 46,000 women recruited during the late 1960s.
Methods Directly standardised incidence rates of multiple sclerosis were calculated for current, former and never-users of oral contraceptives using first ever cases of multiple sclerosis reported by the general practitioners. The standardisation variables were age, parity, social class and smoking history. Five-year survival rates in the different contraceptive groups were calculated using standard life table techniques.
Results One hundred and fourteen first ever cases of multiple sclerosis had been reported by November 1996 during 564,000 woman-years of observation. The incidence rate in both current and former users was not materially different to that in never-users. Although based on limited evidence there was no suggestion that the five-year survival was affected by a woman's use of combined oral contraceptives.
Conclusions These findings do not suggest a greatly elevated risk of multiple sclerosis during, or after, use of combined oral contraceptives.     

The Combined Contraceptive Vaginal Ring: an Update

The combined contraceptive vaginal ring releases 120 μg of etonogestrel and 15 μg of ethinylestradiol per day for at least a 3-week period. It is as effective as combined oral contraceptive pills with similar side effects but better cycle control. The ring is not associated with weight gain and may have many non-contraceptive benefits including a positive effect on sexual function, dysmenorrhea, premenstrual syndrome, and heavy menstrual bleeding. Contraindications are the same as for combined oral contraceptives, and serious complications are rare. The risk of venous thromboembolism with the ring is comparable with that of combined oral contraceptives. The rate of acceptability of the ring is high, and most women, including adolescents, can use the ring.     

Use of oral contraceptives in women of older reproductive age

Evidence of increased risk for cardiovascular disease in oral contraceptive users of older reproductive age is based on early data involving formulations containing higher doses of estrogen and progestin than those in use today. In addition, early studies included patients who would not receive oral contraceptives with today's more stringent prescribing criteria. When these data were carefully analyzed, a significant increase in myocardial infarction was noted only in oral contraceptive users with concemitant risk factors for cardiovascular disease. Analysis of other studies also showed a significant increase in the incidence of cardiovascular disease and mortality only in oral contraceptive users older than age 35 years who smoked. A recent long-term cohort study of women without risk factors for cardiovascular disease who mainly used oral contraceptives containing ≤50 μg estrogen showed no increased risk of myocardial infarction or cerebrovascular accident with oral contraceptive use. Use of oral contraceptives containing <50 μg estrogen has not been shown to be associated with an increased risk of cardiovascular disease in healthy, nonsmoking women 35 to 45 years of age.