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Contraception - Management
What are the advantages, disadvantages, and risks of using combined oral contraceptives (COCs)?
- Advantages:
- Combined oral contraceptive (COCs) are more effective at preventing pregnancy than barrier methods. For more information, see Effectiveness of contraceptives.
- Sex need not be interrupted to use contraception.
- Menstrual bleeding is usually regular, lighter, and less painful [FFPRHC, 2007b].
- Reduced risk of cancer of the ovary, uterus, and colon (Table 1).
- Reduced severity of acne in some women [Arowojolu et al, 2007].
- Reduced risks of functional ovarian cysts and benign ovarian tumours (Table 1).
- Normal fertility returns after stopping the COC.
- Disadvantages:
- Some women experience temporary adverse effects when they start COCs; these include headaches, nausea, breast tenderness, and mood changes [BNF 53, 2007]. If these do not stop within a few months, changing the type of COC may help.
- Blood pressure may increase [FFPRHC, 2007b].
- The COC does not protect against sexually transmitted infections; people at risk for sexually transmitted infections are advised to use condoms as well.
- Breakthrough bleeding (unexpected bleeding on pill-taking days) and spotting is common in the first few months of use; if this persists, it can be treated. For more information see Unscheduled bleeding.
- They are less effective than long-acting reversible methods of contraception (such as progestogen-only implants or injectables, copper intrauterine devices, levonorgestrel-releasing intrauterine system).
- Risks of some rare but serious conditions are increased [FFPRHC, 2007b]:
- Myocardial infarction (heart attack) and stroke:
- Very small increase in risk. The risk is greatest in women who smoke, and those that are diabetic, have high blood pressure, are very overweight, have migraines with aura, or who have a family history of premature atherosclerotic cardiovascular disease.
- Venous thromboembolism (blood clots):
- Risk may be increased as much as five times, but the absolute risk is very low (less than 1% of the risk of coronary heart disease) and considerably less than the risk of venous thromboembolism in pregnancy.
- The risk is greatest in women with previous thromboembolism and those who require prolonged immobilization.
- Breast cancer:
- There is a possible small increase in risk, which returns to no increased risk within 10 years after stopping the COC.
- Cervical cancer:
- There is a very small increase in risk, which increases with longer duration of COC use.
- Table 1 summarizes risk data for non-smokers who use COCs. Smokers have different baseline risks than non-smokers but are likely to have similar changes in risk.
- For information on avoiding risks, see:
- Benefits which have been claimed for COCs but for which supporting data are inadequate [FFPRHC, 2007b]:
- Benign breast disease: reduced risk.
- Osteoporosis: reduced risk. Although the data are conflicting, no study has found a decrease in bone mineral density.
- Adverse effects which have been claimed for COCs, but for which supporting data are inadequate include:
- Weight gain:
- A Cochrane systematic review found that COCs have no large effect on body weight. However, data were insufficient to determine the effect with any precision [Gallo et al, 2006].
- Loss of libido:
- Studies that have suggested that libido can be lost after taking COCs have received wide publication. However, reviews of the literature find studies in which libido was increased, decreased, or unchanged. Results differ according to study design (retrospective and uncontrolled, prospective and controlled, randomized and controlled) [Davis and Castano, 2004; FFPRHC, 2005c; Schaffir, 2006].
- The Family Planning Association provides useful information leaflets for users of COCs and other contraceptive methods — see www.fpa.org.uk.
Table 1. Potential harms and benefits of combined oral contraceptives (COCs) in non-smokers. Smokers have different baseline risks — shown for non-smokers in the middle column of the table — but are likely to have similar changes in risk.
Disease | Rates per 100,000 women not using COC | Change in risk with COC use |
|---|
Potential harmsa (increased risk for condition) |
Coronary artery diseaseb | 1500 | Very small increased risk |
Ischaemic strokeb | 100 | Two-fold increase in ischaemic stroke |
Venous thromboembolismc | 50–100d | Three-fold increase with COCs containing levonorgestrel or norethisteronee Five-fold increase with COCs containing desogestrel or gestodenee About a four-fold increased risk with COCs containing drospirenone (Yasmin®)h |
Breast cancerf | 1 in 9 women will develop breast cancer at some time in their lives. Estimated risk of developing breast cancer: Up to age 30 years: 1 in 1900 Up to 40 years: 1 in 200 Up to age 50: 1 in 50 | Any increased risk likely to be small and will vary with age No increased risk above background risk 10 years after stopping COC |
Cervical cancer | 11 | Small increase after 5 years and a two-fold increase after 10 years |
Benefits (decreased risk for conditions) |
Ovarian cancer | 22 | Halving of risk, lasts for > 15 years |
Endometrial cancer | 15 | Halving of risk, lasts for > 15 years |
Colorectal cancer | g | Relative risk 0.82 (95% CI 0.74–0.92). |
COC = combined oral contraceptive. aInterpretation of potential harms: 1 in 100,000 risk of being affected by a disease is judged to be a negligible risk and equates to one person in a large town being affected. The preceived risk, however, can depend on how the information is given, and the seriousness and incidence of the disease. bStatistics from National Statistics ( www.statistics.gov.uk). Prevalence of treated coronary heart disease and stroke recorded in general practice in England and Wales for women up to 54 years of age. c The relative risk of venous thrombooembolism associated with COC use increases three-fold, but the absolute risk increases from 5 to only 25 per 100,000 woman-years. d A recent study found background rates of venous thromboembolism (VTE) to be 10–20 times greater than that assumed in studies of the risk for VTE in women using COCs [Heinemann and Dinger, 2007]. e All COCs increase the risk of venous thromboembolism, including those containing norgestimate, drospirenone, and cyproterone acetate. g Comparable incidence rate not available. h Data from two large prospective cohort studies suggests that the risk of VTE in women using Yasmin ® is greater than the risk of VTE in women using a levonorgestrel-containing COC, but less than the risk in women using a COC containing desogestrel or gestodene [MHRA, 2010]. |
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