From the Guidelines
Oral contraceptive pills (OCPs) can increase blood pressure in some women, with a typical increase of 0.7 mmHg in systolic blood pressure and 0.4 mmHg in diastolic blood pressure, as reported in a large cross-sectional study 1. This effect is more common with combined hormonal contraceptives that contain both estrogen and progestin, particularly those with higher estrogen doses. The mechanism involves estrogen's effects on the renin-angiotensin-aldosterone system, which regulates blood pressure, and its ability to increase angiotensinogen production in the liver. Women with pre-existing hypertension, those over 35, smokers, and those with other cardiovascular risk factors are at higher risk for blood pressure increases. Progestin-only pills ("mini-pills") like norethindrone 0.35mg daily are less likely to affect blood pressure. Some key points to consider when prescribing OCPs include:
- Blood pressure should be checked before starting OCPs and monitored regularly during use, especially in the first few months.
- If a significant increase occurs, switching to a lower-dose estrogen pill, a progestin-only method, or a non-hormonal contraceptive option may be necessary.
- Women with well-controlled hypertension can often use low-dose combined OCPs safely, but those with uncontrolled or severe hypertension should generally avoid estrogen-containing contraceptives, as supported by the seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure 1. It is essential to weigh the benefits and risks of OCPs in each individual patient, considering factors such as age, medical history, and lifestyle, to minimize the risk of adverse effects on blood pressure. In general, the use of OCPs should be approached with caution in women with hypertension or those at high risk of developing hypertension, and alternative contraceptive methods should be considered when possible. The most recent evidence suggests that the association between OCP use and hypertension is smaller than previously thought, but still significant, highlighting the need for regular blood pressure monitoring and careful patient selection 1.
From the Research
Oral Contraceptive Pills and Blood Pressure
- Oral contraceptive pills (OCPs) can increase blood pressure in some women, with an incidence of OCP-induced hypertension ranging from 1-8.5% among OCP users 2.
- The risk of hypertension is higher in women with certain risk factors, such as age, BMI, past personal and family history of hypertension, and alterations in hormonal metabolism and the renin angiotensin aldosterone system 2.
- Combined oral contraceptives (COCs) are associated with an increased risk of arterial and venous thromboembolic events, with the highest risk of venous thromboembolism occurring in the first year of use 3.
- The use of COCs can increase the risk of myocardial infarction and stroke, particularly in women over 35 years old and those with poorly controlled hypertension 4, 3.
- Progestogen-only contraceptives (POCs) may be a safer alternative for women with multiple cardiovascular risk factors, as they are associated with substantially less risk of cardiovascular events than COCs 3.
Contraception and Hypertension Management
- Blood pressure level should be assessed before initiation of oral contraceptives, and women with hypertension should be carefully monitored while using OCPs 5.
- Women with self-reported hypertension are less likely to use non-barrier contraception, and those who do use non-barrier contraception are often using estrogen-based methods that can raise blood pressure 6.
- Contraceptive counseling should take into account the individual woman's risk factors and medical history, and should include discussion of the potential risks and benefits of different contraceptive methods 5.