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Oral Contraceptives

Birth Control Pills

What are oral contraceptives?

Oral contraceptives (OCs) are any kind of birth control tablets taken by a women to prevent pregnancy. Oral contraceptives are synthetic hormones prescribed by a doctor and purchased by prescription. There are several types of oral contraceptives, some of these contain only one type of hormone (progestin-only pills) and some contain two (combined oral contraceptives). Most oral contraceptives are taken daily, but some are taken 21 days per month.

How do oral contraceptives work?

Oral contraceptive pills are believed to work by multiple mechanisms. Combined oral contraceptives contain estrogen and progestin, which are artificial variations of natural female hormones.

  1. In most cases the drugs prevent ovulation. No egg is released so sperm cannot fertilize it.
  2. OCs may also prevent fertilization by changing the consistency of natural secretions in the vagina, making it harder for the sperm to reach the egg.
  3. Women may experience breakthrough ovulation which can lead to fertilization. When this occurs, OCs work by making it harder for the embryo to implant in the womb by keeping the lining of the uterus thin.

Progestin-only pills (also called estrogen-free or the mini-pill) utilize the same mechanisms, but are less likely to prevent ovulation and more likely to use this thrid mechanism.

How effective are oral contraceptives?


Annual Failure Rate

Oral contraceptives have an overall annual failure rate of 7%. That means each year about 1 in 14 users experience an unplanned pregnancy. Oral contraceptives have a lower annual failure rate of 6% for married couples, but a higher rate of 14% for cohabiting couples. Oral contraceptives are also less effective for teens and couples in their early twenties, with a failure rate of about 14%. Pills higher in estrogen will be more effective, and estrogen-free pills are less effective.

Side-effects and health risks of oral contraceptives:

There are many potential side-effects, health risks, and drug interaction concerns involving oral contraceptives. A few are listed here, but not all are provided due to space limitations.

Problems caused by Estrogen Problems caused by Progestin
Breast swelling & tenderness
Vaginal discharge
High blood pressure
Decreased sex drive
Mood swings
Fluid retention
Permanent dark patches on face
Drug interaction problems
Gallbladder disease
Eye or vision problems
Embolism (rare)
Heart attack (rare)
Stroke (rare)
Breast tumor growth (rare)
Weight gain
Fatigue and tiredness
High blood pressure
Acne and/or oily skin
High cholesterol
Insulin resistance
Irregular menstrual bleeding
Breast tenderness
Heart attack (rare)
Breast tumor growth (rare)

Considerations for Christians:

Most medical organizations define pregnancy as beginning with implantation. By this definition anything that prevents implantation is still considered contraception, including oral contraceptives. However, life begins when fertilization occurs, so many Christians would consider oral contraceptives an abortifacient -- a drug that causes a very early abortion. These medical facts have been controversial because many Christian doctors prescribe OCs and many Christians take oral contraceptives without full knowledge of this information. This is not an accident. Pharmaceutical companies downplay the abortive mechanism to keep Christian women buying their products.

Related Links

Source for Failure Rates: N Ranjit, A Bankole, JE Darroch, S Singh, "Contraceptive Failure in the First Two Years of Use: Differences Across Socioeconomic Subgroups," Family Planning Perspectives, 2001, 33(1):19-27. (pdf)

A Couple's Guide to Better Birth Control, Conscientious Contraception, and Sensible Sexuality

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What's in Your Pill?

Types of Estrogens
  • ethynil estradiol
  • mestranol
Types of Progestins
  • desogestrel
  • drospirenone
  • ethynodiol diacetate
  • levonorgestrel
  • norethindrone
  • norgestimate
  • norgestrel

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