Oral Contraceptives

Oral contraceptive pills (The Pill) are extremely popular due to their ease of use and efficacy. Oral contraceptives come in many formulations and brands, including low dose and estrogen-free versions; these have fewer unwanted side-effects, but are less effective. Oral contraceptives (OCs) are available by prescription only. Like all hormonal contraceptives, OCs have multiple mechanisms of action, some which prevent ovulation and others that occur after fertilization.

Combined Oral Contraceptives (The Pill)

Average Failure Rate: 3 - 8%

The process of ovulation is directed by hormones. Estrogen and progesterone are two hormones which direct many of the processes surrounding the menstrual cycle. Artificial analogues of these have proven an efficient form of birth control. To prevent pregnancy a woman takes a pill daily which contains both of these hormones. This is the combination pill, or simply "The Pill."

The estrogen works by preventing an egg from being released from the ovaries most of the time. Both the estrogen and progesterone make the uterus a hostile environment for an embryo by causing a thinning of the uterine lining. As modern combination pills contain less estrogen than their predecessors, an egg will be released by the ovaries 2-10% of the time. If fertilization takes place, the embryo will be unable to implant in the uterus, resulting in the death of the embryo. Although some consider this risk minimal, the most reliable sources cite the interceptive effect as a major mechanism of action; in fact, large doses of this drug are used as a 'morning after pill' (see the Emergency Contraceptive Pills page).

Oral contraceptives also have some uncommon but serious health risks associated with their use, especially among smokers; these include abnormal blood clotting and heart attacks, cancer, and gallbladder disease. Side effects include loss of sex drive (libido), headaches, acne, weight gain, vaginal infections, and depression. Current research indicates that oral contraceptives increase your risk of acquiring HIV if your partner is infected.

Progestin-Only Oral Contraceptives (Mini-Pills)

Average Failure Rate: 1 - 13%

Progestin based oral contraceptives, commonly referred to as "the mini-pill," contain progestin but no estrogen. The mini-pill works by changing the lining of the uterus which prevents the implantation of an embryo and inhibiting ovulation in some women. Many women taking the mini-pill will continue to ovulate every month, and those women who do cease ovulating will usually stop having periods altogether. 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.

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 also considered safer than combined OCs, as many of the vascular risks are markedly reduced with the omission of the estrogen component. Health risks and side effects include ectopic pregnancy, depression, and menstrual cycle disturbances. Current research indicates that oral contraceptives increase your risk of acquiring HIV if your partner is infected.

Featured Links

• Contraception while Breastfeeding
• 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
• Oral Contraceptives: Yasmin Info for Doctors (pdf)
• Oral Contraceptives: Yasmin Info for Patients (pdf)
• Oral Contraceptives: Orthocept Info for Patients (pdf)
• Oral Contraceptives: Micronor Detailed Patient Labeling (pdf)
• Oral Contraceptives: Ortho Novum Detailed Patient Labeling (pdf)
• Oral Contraceptives: Ortho Tricyclen Info Detailed Patient Labeling (pdf)
• Oral Contraceptives: Ortho Tricyclen Lo Info Detailed Patient Labeling (pdf)

• Ethical Issues Regarding Post-Fertilization Effects of Oral Contraceptives: A physician discusses the ethical reasons he has decided to stop prescribing oral contraceptives, excerpted from Archives of Family Medicine, 2/2000
• Does the Birth Control Pill Cause Abortions? by Randy Alcorn
• Do Contraceptives Cause Abortions? A look at both pro-life and pro-choice definitions
• Pharmacy has a Conscience Problem: Pharmacist fired for refusing to fill prescription for abortifacient
• Who Should Not Use OCs
• Forgetting the Pill: Timers for Pill users, instructions for what to do if you miss a pill
• Pharmacists for Life International
• More about Oral Contraceptives: Christian Contraception

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