Birth control pills are oral contraceptives that prevent pregnancy. They are 98-99% effective at preventing pregnancy, if taken correctly. Delaying or missing even one pill significantly reduces their effectiveness. Oral contraceptives are also used to regulate menstrual periods.
From an economic standpoint, the ability to control fertility independently allows women to make long term educational and career plans.
Combination birth control pills contain the hormones estrogen and progestin. Progestin is a synthetic form of the hormone progesterone. Most combination pills use the same form of estrogen (ethinyl estradiol), but different types of progestins.
Birth control pills differ in the way the estrogen and progestin are distributed over the cycle.
There are three types of combination pills: monophasic, biphasic, and triphasic.
Multiphasic pills contain varied amounts of hormones which are designed to be taken at specific times throughout the course of each package. These contraceptives were developed in an attempt to decrease the side effects of monophasic pills. Multiphasic birth control pills tend to lower the total hormone dosage a woman receives during the cycle.
One-phase pills contain the same amount of hormone for three weeks.
The packages usually contain 21 days of active pills along with seven inert sugar pills. The oral contraceptive is taken for three weeks of the cycle, followed by seven days of sugar pills. This maintains a 28-day cycle. Women usually have their period within a couple of days of starting the sugar pills.
If a woman continued to take the active and not use the sugar pills, she apparently would not menstruate. Sometimes women use this technique to "skip" a period.
Note: The "skipping" technique can be realized only with monophasic contraceptives.
Seasonale is a monophasic birth-control packaged in a 91-day supply and is designed to prevent menstruation for the entire time period. Women taking Seasonale will have only four periods a year. Although many other monophasic birth control pills may be used in this way, Seasonale is the only product approved by the FDA for such use.
Examples of monophasic pills:
Biphasic pills have a fixed amount of estrogen, but there are two different strengths of progestogen. The first 7 to 10 days are one strength (and one color), and the next 11 to 14 pills are another strength (and another color). The last seven are placebo and contain no hormone.
Examples of biphasic pills:
Depending on the brand, the amount of estrogen may change as well as the amount of progestogen. There are actually three different doses in the dispenser. The hormone combination (and the color) changes approximately every 7 days throughout the package.
Examples of triphasic pills:
Minipills or progestin-only pills (POP) contain only one hormone, progestin. All the pills are identical. Minipills are slightly less effective than combined birth control pills. Even missing one minipill can greatly reduce effectiveness.
They are appropriate for women who have conditions that prevent them from taking estrogen.
Examples of minipills:
Emergency contraceptives, also called "the morning after pill", are used to prevent pregnancy after unprotected sex. Emergency contraception is most effective the sooner it is taken after sex.
In the United States, there is only one FDA-approved ECP called Plan B. However, number of brands of regular oral contraceptives also can be used as ECPs.
In general, progestin-only emergency contraceptives are more effective than combined ones. Labeling for Plan B and other emergency contraceptives that contain only the hormone progestin states that they reduce the risk of pregnancy by 89%.
See also for woman's health:
Last updated: March, 2013