For many women, contraceptive choice involves personal preference but for some these choices can be limited.
Women using combined oral contraceptives (COCs) with high BP (over 160/100 mmHg) in the absence of vascular disease should not be started or continued on COCs because of the increased risk of stroke, MI and vascular disease. Progestogen-only pills (POPs), implants, IUDs or intrauterine systems (IUS) are suitable.
Even if the hypertension is adequately controlled or borderline (less than 160/95) and there is no vascular disease, COCs are not usually recommended. POPs or injectables such as medroxyprogesterone acetate would be the preferred choice as they can be used without any restrictions.
If vascular disease is present with hypertension, copper IUDs can be used without restriction. Other methods where the advantages generally out-weigh the risks are POPs, implants and IUS.
Progestogen-only injectables are not recommended in patients with vascular disease, and COCs should not be used, according to the UK Medical Eligibility Criteria.
Some drugs interact with hormonal contraception by enhancing metabolism of estrogens and progestogens in the liver. These hepatic enzyme- inducing drugs include barbiturates, carbamazepine, rifampicin, phenytoin, griseofulvin and some antiviral drugs.
COCs, vaginal rings and patches are not suitable for women on these medications, nor are POPs and implants. However, progestogen injectables, copper devices and IUS can be offered. For emergency contraception in this context, an initial dose of 3mg of levonorgestrel should be used.
Women on certain medications that are not liver enzyme-inducers (such as gabapentin, sodium valproate, lamotrigine and some antibiotics) can have all forms of contraception providing that there are no other contraindications.
Antibiotics can alter colonic bacteria, leading to reduced absorption of hormonal contraceptives. Condoms should be used for the duration of a short course of antibiotics and for the following seven days, and for the first three weeks of a long course.
Except for griseofulvin, antifungals can generally be used without any restrictions. Women on antiviral therapy are usually suitable for most forms of contraception. HIV-positive women should also be advised to use condoms to reduce the risk of transmission and in case of reduced efficacy.
The dose of the COC in patients on lamotrigine may need to be adjusted, as both drugs may be less effective when used together. To ensure reliability, it may be best to use alternative contraception. Women taking St John's wort should not be given COCs, progestogen pills or implants.
|UK Medical Eligibility Criteria (UKMEC) categories|
Condition with no restriction on contraceptive method
Advantages generally outweigh risks for contraception
Risks outweigh advantages for contraception
Unacceptable health risk of contraception
Contraception and obesity
The risk of venous thromboembolism increases with BMI and the use of COCs adds to that risk.
There is also a risk of contraceptive failure in obese patients. Women in the BMI range 30-34kg/m2 usually have an unrestricted choice if there are no other contraindications.
If the BMI is >35kg/m2, COCs are not recommended, including delivery via vaginal rings and patches. If a woman weighs more than 70kg, the dose of some POPs may need to be adjusted to ensure efficacy.
With implants, levels of etonogesterel are inversely related to body weight and decrease with time. Data are limited, but the replacement of implants earlier than the recommended three years might be considered.
Weight gain is one of the most frequently cited reasons for stopping hormonal contraceptives, and many women believe it is related to oral contraceptive use. However there is little evidence to suggest that hormonal contraceptives increase weight.
Nevertheless, estrogens might possibly increase fluid retention by acting on the renin-angiotensin-aldosterone system, and could also increase appetite.
The combination of drospirenone and ethinylestradiol could in theory counteract the fluid retention caused by the estrogenic component of the combined pill because drospirenone has androgenic and antimineralocorticoid activities. It should not be taken with potassium-sparing diuretics or other drugs acting on the renin-angiotensin system.
Some trials have shown an increase in serum HDL and triglyceride concentrations in patients on drospirenone and ethinylestradiol, when compared with levonorgestrel/ethinylestradiol combinations.
This COC might be useful for women who suffered from fluid retention or weight gain and breast tenderness when on other COCs, and in those with mild to moderate acne. IUDs or low dose hormonal contraceptives could also be tried.
Polycystic ovary syndrome (PCOS) occurs in about 20 per cent of women with subfertility. However women with PCOS can often still conceive naturally, and may need contraception.
In those women with reduced or absent periods, a withdrawal bleed should be induced at least once every three months to prevent endometrial hyperplasia. This can be achieved with a COC or cyclical progestogen if estrogens are contraindicated. The IUS is another option.
- Dr Aziz is a GP in Bristol