Progestin-Only Oral Contraceptives (Estrogen-Free Pills)
Average Failure Rate: 1 - 13%
About The Mini-Pill
Progestin-Only Pills (POP), also called the mini-pill, are estrogen-free oral contraceptive pills taken daily to prevent pregnancy. Oral contraceptive pills come in many formulations and brands, and the estrogen-free mini-pill has fewer unwanted side-effects than traditional combined oral contraceptives. The trade-off is that mini-pils are less effective and can cause irregular menstruation. Popular brands of progestin-only pills include Micronor, Nora-BE, and Nor-QD. Estrogen-free oral contraceptives are available by prescription only.
How Progestin-Only Oral Contraceptives Work
Like all hormonal contraceptives, the mini-pill has multiple mechanisms of action, some which prevent ovulation and others that occur after fertilization but before implantation.
Progestin is a female hormone that can inhibit ovulation, so no egg means that the male sperm cannot fertilize it. These women will usually stop having periods altogether. However, many women taking the mini-pill will continue to ovulate every month (about half), and in these cases changes to the lining of the uterus will prevent the implantation of an embryo. The progestin may also cause a thickening of cervical mucus, making it harder for sperm to reach the egg. This effect on cervical mucus, however, starts to drop off sharply if a woman is only a few hours late in taking her next pill, thus it is critical that pills be taken at the same time every day.
"I feel chemical contraceptives have the potential to harm an embryo. And I decided based on moral and ethical grounds that I could no longer prescribe them." - Mary Martin, MD, Ob/Gyn, Midwest City, OK [more about this]
Benefits of Progestin-Only Oral Contraceptives
Doctors tend to recommend the mini-pill to breastfeeding women because it does not reduce the amount of milk produced, although there have been concerns about exposing the new infant to unnecessary steroids. Mini-pills are also considered safer than combined OCs, as many of the vascular risks are greatly reduced with the omission of the estrogen component. That means less risk for older women, smokers, and those with heart problems.
Side Effects and Health Risks of Progestin-Only Oral Contraceptives
Health risks and side effects include ectopic pregnancy, depression, and menstrual cycle disturbances. Oral contraceptives do not protect against STDs, and current research indicates that oral contraceptives increase the risk of acquiring HIV from an infected partner.
Drug Interactions for Oral Contraceptives
Certain medications have been known to decrease the effectiveness of progestin-only oral contraceptive pills. These include antibiotics, anticonvulsants, certain anti-HIV drugs, and the herbal supplement St. John's Wort.
Contraception while Breastfeeding
Combined Oral Contraceptives
Hormonal Methods Overview
Post-Fertilization Effects of Hormonal Methods: The Controversy
Frequently Asked Questions about the Pill and Other Hormonal Methods
Future Birth Control Methods
Use of Contraceptives
Low Dose Oral Contraceptives