A number of contraceptives are based off the use of hormones by women to prevent pregnancy. These methods are generally very effective at preventing unwanted pregnancy, but do not reduce the transmission of STDs at all. It is important, therefore, that partners using hormonal contraceptives also use barrier contraceptives to protect against disease.
Combined hormonal contraceptionEdit
The most common hormonal methods use both a synthetic version of estrogen, and a synthetic version of progesterone (called a 'progestin'). The most common method is "the pill," but these hormones may also be delivered through a patch that adheres to the skin, or a flexible plastic ring that is inserted into the vagina.
Combined hormonal methods work by preventing ovulation. They also have possible back-up effects of changing the mucus produced by the cervix (to prevent sperm from getting inside the uterus), and of making it difficult for any embryo to implant in the uterus.
The Pill is taken orally every day. To be effective, it must be taken within 12 hours of the same time each day. The Pill usually comes in packages of 28 pills. The first 21 pills are "active" pills that contain hormones. The last seven pills are "inactive", or "placebo" pills. Inactive pills do not contain hormones, and are just there to help a woman remember to take a pill every day. When a woman stops taking active pills, she will have "withdrawal bleeding", usually called a period.
There are two main types of pills. Monophasic pills have the same amount of hormones in every active pill. Bi-phasic or tri-phasic pills have different amounts of hormones (two different levels in bi-phasic, three different levels in tri-phasic). If a woman wants to delay her period, or avoid it altogether, she may take active, monophasic pills every day, with no placebo pills until she is ready to have her period. If this is done for a long time, or if it is attempted with bi- or tri-phasic pills, the woman is very likely to have "breakthrough bleeding".
A recent addition to the lineup of hormonal contraceptives is the patch. The patch goes on the skin, and releases hormones through the skin that work the same as the pill. Patches are worn for one week at a time, for three weeks, and then a one-week break is taken to cause a period.
For some women, the patch may cause irritation to the skin. If it persists, such irritation should be brought to the attention of a doctor.
The vaginal contraceptive ring is a flexible plastic ring that is inserted into the vagina. It is worn for three weeks, and then a one week break is taken. The woman will have a period sometime during the break week.
While commonly known as progesterone-only methods, these contraceptives do not actually contain progesterone, but rather a synthetic chemical known as a progestin. The mechanism of action of these contraceptives depends on amount of progestin that is given to the woman.
All progestin-only contraceptives cause changes in cervical mucus that may prevent sperm from entering the woman's uterus. They may also make it more difficult for embryos to implant in the uterus. Contraceptives that deliver a low dose of progestin include traditional progesterone-only pills as well as implants Norplant and Jadelle. These methods prevent ovulation about 50% of the time.
The progesterone-only pill Cerazette and the implant Implanon deliver an intermediate dose of progestin. These methods prevent ovulation about 98% of the time. Injectable methods like Depo-Provera deliver a high dose of progestin. These methods completely inhibit follicular development and ovulation.
Like the combined pill, progesterone-only pills are taken orally every day. While Cerazette has the same 12 hour window of effectiveness as the combined pill, the traditional progesterone-only pills (the mini-pill) must be taken within 3 hours of the same time each day to be effective.
Unlike the combined pill, progesterone-only pills are all active; there are no placebo pills. With the mini-pill, menstruation will still occur, but because the pill sometimes suppresses ovulation, menstruation will be irregular. Some women do not experience any menstruation while on the mini-pill.
Also known as the shot, Depo-Provera is a high dose of progestin injected into the woman with a syringe. The woman must go back to her doctor or health clinic every twelve weeks (three months) to receive a new injection. While irregular bleeding and spotting is a common side effect, regular menstruation will not happen while the woman is on the shot.
Pregnancy may occur if a woman misses an appointment to renew the shot. However, return of fertility varies widely between women, and some women will not get pregnant until a year after their last shot. For this reason, it is recommended that women who want to become pregnant in the near future use a different method of birth control.
Depo-Provera is known to cause loss of bone density. Because of the seriousness of this side effect, the manufacturer does not recommend that women use the shot for longer than two years.
In some women, the shot causes skin irritation around the location of injection.
Previously available was Norplant (a five-rod implant), which was taken off the market due to difficulties removing the rods. The manufacturer now offers a three-rod implant called Jadelle that works in the same way, but is easier to remove. Both Norplant and Jadelle are effective in preventing pregnancy for five years.
Implanon is a single-rod implant that is effective for three years.
No hormonal method protects against STDs.
Combined hormonal methods cause increased risk of blood clots and stroke. Progesterone-only methods do not carry these risks.
All hormonal methods have a possible effect of causing changes in sexual desire, most commonly loss of interest in sex and decreased ability to orgasm, but also possibly an increased sex drive. Depression is also a possible side effect. All women will react differently to hormonal contraceptives, and if a particular hormone or hormone mixture is causing such unwanted side-effects, it is possible that a different type of contraceptive might not have those side effects. Consult your doctor to discuss your contraceptives.