Oral Contraceptive Tolerance. Does the Type of Pill Matter? Obstetrics and Gynecology (2007); 109 (6): 1277-84

Oral contraceptive pills (OCPs) have been the most popular form of reversible contraception for several decades and are currently used by about 100 million women worldwide. There has been growing concern over the related adverse effects, which has led to substantial changes in their composition. OCPs differ according to the dosage of estrogen (15-50mcg per day), the type of progestin (generally classified in generations), the sequence of administration (either monophasic or multiphasic) and the number of active pills per cycle.

In order to improve compliance a balance between cycle control and adverse effects needs to be struck.

In this cohort study, the authors investigate the frequency of several reported symptoms, according to the type of OCP used, among 2,863 French women of reproductive age. They were followed up annually for 4 years with 1,568 women remaining in the study for the 4 years.

The most common symptoms reported where recent weight gain (25.2%), painful periods (20.7%), swollen legs (20.9%) and heavy menstrual bleeding (15.6%). There was little variation in the frequency of these symptoms with different OCPs.

Painful menstrual periods and breakthrough bleeding or heavy menstrual bleeding were more frequently reported at the start of pill use (1 year or less) than for longer durations of use. They were also more likely to report pain during their menstrual cycle.

This study agrees with other trials that there is an increased likelihood of abnormal bleeding patterns and lower frequencies of menstrual periods among progestin-only pill users, which persists over time. This is the most common reported reason for discontinuation.

There was no evidence to suggest a decrease in symptoms with decreasing estrogen doses, nor with monophasic or triphasic administration. Prescribers are increasingly favouring of the lowest estrogen dose formulations (20mcg) combined with 3rd-generation progestins (desogestrel, norgestimate) which are claimed to be better tolerated than the 2nd-generation progestin (levonorgestrel) because of their reduced androgenic effects. This study however did not support this hypothesis.

In summary, there is little evidence to support varying tolerance to combined OCPs and more rigorous studies are required. This paper does also suggest that future research should assess the effectiveness of counselling on the tolerance of OCPS, an intervention that may prove more beneficial than choosing an OCP on their theoretical properties.