Abstract

PIP: This commentary reviews the indications for and side effects of the progestogen-only oral contraceptive (OC) pill, which accounts for under 3% of hormonal contraceptive sales in the UK. The progestogen-only pill has the advantage of fewer metabolic changes, a lower dose of progestogen, and avoidance of the use of estrogen. It is the hormonal method of choice for breast feeding women, older women, and women who are unable to tolerate an estrogen-containing preparation. Its failure rate ranges from 0.9 to 3.0/100 woman-years, which is comparable to that for other reversible methods. The failure rate tends to be lower in older age groups, perhaps reflecting advancing sensitivity with age to the contraceptive effects of progestogen. The major problem associated with use of progestogen-only contraceptives is irregular vaginal bleeding, experienced by 20-30% of users. Progestogen has been reported to induce a variety of effects on the endometrium as well as in ovarian steroid secretion. A high prevalence of functional ovarian cysts has been noted in users. It is now believed that the contraceptive efficacy of the progestogen-only pill depends more upon its effects on ovarian function than was previously realized. A new approach to overcoming some of the problems associated with progestogen-only contraception has involved combining progestogen with sulpiride. This combination appears to be more effective than either component alone in suppressing ovarian activity. There is a need to make progestogen-only OCs more widely available to women in developing countries, where 30-40% of women of reproductive age may be breast feeding at a given time. Numerous studies have demonstrated either no effect or a beneficial effect on lactation.