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Encyclopedia > Oral contraceptives

Oral contraceptives are contraceptives which are taken orally and inhibit the body's fertility by chemical means. Female oral contraceptives have been on the market since the early 1960s. Male oral contraceptives remain a subject of research and development, and are not available widely (if at all) to the public. Studies continue of various alternatives, such as gossypol.


The Pill

Female oral contraceptives, colloquially known as the Pill, are the most common form of pharmaceutical contraception, the prevention of unwanted pregnancy. They consist of a pill that women take daily and that contains doses of synthetic hormones (estrogen and progesterone); the doses are adjusted in synchrony with the menstrual cycle. It is used by millions of women around the world, though the acceptance varies by region: approximately one-third of sexually active women in the United Kingdom use it, while in Japan what amounts to a boycott by doctors making huge profits from abortion has led to the pill being banned for nearly 40 years, and its recent introduction has seen very few women take it up.

Mechanism of action

The Pill works by preventing ovulation, as well as making the uterus less likely to accept implantation of an embryo if one is created, and thickens the mucus in the cervix making it more difficult for sperm to reach any egg. Taken correctly, it is the single most reliable form of reversible contraception, with less than one in 100 women using the pill becoming pregnant in a year of continuous use.

Several different types of 'the pill' exist. Generally, they all have revolve around different formulations of (chemical analogues of) the hormones estrogen and progesterone. Most brands use 20 to 40 micrograms of ethinyloestradiol as the estrogen component and either a fixed or varying (the bi and triphasic pills) amount of progestogen as the progesterone analogue.


Half-used blister pack of LevlenŽED
Half-used blister pack of LevlenŽED

The pill usually comes in two different packet sizes, and each packet usually has days marked off for a cycle lasting about a month, or 28 days to be exact. For the 21-pill packet, a woman takes a pill each day for 21 days, and waits for an additional seven days before starting the next packet. For the 28-pill packet, the woman similarly takes a pill each day. However, instead of only taking pills for 21 days of the month, she also takes the remaining seven placebo or sugar pills pills included in the packet, and once she finishes the last placebo pill, she can immediately start the next packet on the following day. The purpose of the placebo pills is to ensure that the woman, out of habit, can take a pill on every day of her menstrual cycle, so that she does not have to calculate when exactly is the next date that she should start her next packet of pills. It is possible for a woman to skip menstruation and still remain protected against conception by skipping these pills in the cycle. The presence of these pills is still thought to be comforting for the woman as menstruation is a physical confirmation that she is still not pregnant.

Drug interactions

Some drugs reduce the effect of the pill and can cause breakthrough bleeding, or worse, pregnancy (together with unprotected sex, of course). These include antibiotics, barbiturates, phenytoin and carbamazepine. The traditional medicinal drug St John's Wort has also been implicated.

Cautions and contraindications

Serious side effects that would indicate a need to discontinue the pill include: pain or swelling in the thigh or calf, severe headaches, hypertension, dizziness, weakness, vision problems, chest pain or shortness of breath, abdominal pain.

These serious side effects are a result of the pill affecting coagulation, increasing the risk of blood clots causing DVTs (deep venous thrombosis), stroke and heart attacks. This is especially so in women who already have some pre-existing vascular disease, in women who have a familial tendency to form blood clots (such as familial factor V Leiden), women with hypercholesterolaemia (high cholesterol level) and in smokers.

Side effects

When starting to take the birth contol pill some people may expierence slight weight gain, although this depends entirely on the individual and some people experience no weight gain at all while people who are already obese or overweight may continue to gain weight. Some people also notice changes in the intensity of sexual desire, vaginal discharge and menstrual flow. Some other common side effects are: nausea; headaches;, depression; vaginitis; urinary tract infection; breast changes; skin problems; and gum inflammation.

The main causes of these are the way individuals react to the chemicals in certain types of pill.

Other risks

The pill slightly increases the risk of breast cancer, while slightly decreasing the risk of ovarian cancer and uterine cancer. In rare cases, high estrogen pills may trigger pseudotumor cerebri, also known as benign intracranial hypertension.

The pill as a form of abortion

In cases when the pill prevents the implantation of an embryo, this may be considered a form of chemically induced abortion since the egg is actually fertillized at this point. It has not been determined how frequently the abortifacient mechanism occurs, but the lower the dose of estrogen the more likely ovulation is to occur -- increasing the chances for an egg to be fertilized. Women taking the lowest-dose pills available may ovulate up to 20% of the months spent on the pill, but it is impossible to determine in how many of those months the egg is fertilized. Some therefore reject oral and other chemical contraceptives in favor of natural family planning (the only method of contraception allowed by the Catholic Church) or barrier methods such as condoms. The medical community generally does not consider this to be an abortion at this early stage - the medical community defines an abortion as the termination of a pregnancy, and defines pregnancy as beginning with the implantation of a zygote in the wall of the uterus.

History and social impact

The invention

Carl Djerassi (1923-) invented norethindrone in the 1950s..

The sexual revolution

The Pill's development in the early 1960s and FDA approval of the drug on May 9, 1960, was one of the major factors leading to the sexual revolution that occurred later in the decade.

See also

  Results from FactBites:
FDA's Approval of the First Oral Contraceptive, Enovid (445 words)
The first oral contraceptive was submitted first for regulatory approval in 1957 as a treatment for menstrual disorders and infertility, not as a contraceptive (although the drug had been developed as an oral contraceptive).
In judging the safety of the first oral contraceptive, regulators were most concerned about it ability to prevent pregnancy because pregnancy and delivery were inherently medically risky.
The chief danger of oral contraceptivesž thromboembolism (occasionally fatal obstructions of blood vessels leading to brain, heart, or lungs)ž was not anticipated by anyone at the time of approval.
Oral contraceptive - Wikipedia, the free encyclopedia (3815 words)
Oral contraceptives are chemicals taken by mouth to inhibit normal fertility.
Generally, all oral contraceptives have different synthetic estrogens and progestins, chemical analogues of the natural hormones, estradiol (an estrogen) and progesterone (a progestagen).
Oral contraceptives may influence coagulation, subtly increasing the risk of deep venous thrombosis (DVT) and pulmonary embolism, stroke and myocardial infarction (heart attack).
  More results at FactBites »



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