Although contraceptive potions, devices, and techniques date back to antiquity, as recently as the early part of this century it was illegal virtually all over the world to provide, print, or disseminate information about birth control. It was largely through the efforts of one woman, Margaret Sanger, that public access to birth control was finally achieved. Sanger, an obstetrical nurse who witnessed the horrors of botched abortions, relentlessly advocated womenís rights to control their own destinies. She is considered the founder of the modern birth-control movement.

Today, a wide variety of birth-control methods is readily available. Your task, if you wish to separate sexual intercourse from conception, is to discover which of them comes closest to meeting your own needs. Safety and reliability are major concerns, of course, but many other factors come into play in making a decision about birth control. These include your health status, your lifestyle, and your attitudes about sex.

Natural methods of contraception that have been practiced for centuries include coitus interruptus, or withdrawal of the penis from the vagina before ejaculation; breast feeding; and natural family planning (formerly called rhythm method), which requires abstinence on the days when a woman is believed to be fertile. All of these methods are unreliable. Modern methods are based on three general approaches: (1) hormones that interrupt ovulation, (2) long-term mechanical interruption of fertilization or implantation, and (3) barriers that keep semen from moving into a female's reproductive tract. The more you know about how the contraceptives work, the better equipped you will be to decide among them.

Hormones

Oral Contraceptives. Oral contraceptives (the Pill) are currently the most popular reversible contraceptive in the United States, used by almost 30% of all women. They usually consist of a synthetic estrogen combined with a synthetic progesterone in the form of pills that are taken daily for 21 days after the last day of a menstrual period. This procedure causes an immediate increase in blood levels of ovarian steroids (from the pill), which is maintained for the normal duration of monthly cycle. As a result of negative feedback inhibition of gonadotropin secretion, ovulation never occurs.

Since the contraceptive pills contain ovarian steroid hormones, the uterine lining proliferates and becomes secretory, just as it does in a normal cycle. In order to prevent an abnormal growth of the lining, women stop taking the pills after 3 weeks (placebo pills are taken during the fourth week). This causes estrogen and progesterone levels to fall, and menstruation follows.

The side effects of earlier versions of the birth-control pill have been reduced by decreasing the content of estrogen and by using newer generations of progestogens (analogues of progesterone). The new pills are very effective (with only about a 2% failure rate) and have a number of beneficial side effects, including a reduced risk of endometrial and ovarian cancer, a reduced risk of heart disease, and reduction in osteoporosis. However, the risk for breast cancer, and possibly cervical cancer, may be increased with oral contraceptive.

Norplant

The Norplant implant, introduced in the United States in 1990, consists of six flexible capsules filled with a progestin, each about the size of a matchstick. The capsules are usually implanted in the hypodermis of the inner arm, below the armpit, and offer protection for 5 years. Although their failure rate is less than 1%, up to 7% women discontinue use because of persistent bleeding problems. Removal of the implant may be difficult, giving Norplant recent negative publicity.

Depo-Provera

An injectable progesterone contraceptive, Depo-Provera has been in use worldwide for over 30 years, but it was not approved for the U.S. market until 1992. A few studies had shown a relationship to cancer in animals, but the millions of women using the drug had no such problem; in fact, they actually showed a decrease in endometrial cancer as a result of taking the drug. Depo-Provera suppresses ovulation for 3 months after it is injected. It has an effectiveness rate of about 99% and carries few side effects, although a small number of women report irregular bleeding, amenorrhea, and weight gain.

The Morning-After Pill and RU486

The theory behind the morning-after pill is that extremely high doses of estrogen over a period of days will prevent implantation of a fertilized ovum. In the United States, the morning-after pill is usually reserved as an emergency measure after rape or contraceptive failure. The side effects of its high estrogen content can be severe, including constant vomiting and water retention.

Another emergency contraceptive is mifepristone (RU486). Developed in France, this so-called abortion pill causes the loss of an implanted embryo by blocking the progesterone receptors of the cells of the uterine lining. If progesterone is prohibited from acting, the lining sloughs off, carrying the embryo with it. When taken in conjunction with a small amount of a prostaglandin to stimulate uterine contraction, about 96% of the women undergoing the procedure have a successful abortion. RU486 can be taken up to 5 weeks after conception. The drug's side effects include cramps and nausea. About one in a thousand women experiences bleeding severe enough to require a transfusion. Vocal pro-life forces in the United States have taken a strong stand against RU486, but many people believe that it will be approved for use soon.

LONG-TERM MECHANICAL INTERRUPTION

IUDs. An intrauterine device is a small plastic or metal object, often molded into a loop, spiral, or T shape. It is inserted into the uterus by a physician, where it can remain in place for at least a year. Only about 3% of the women who use IUDs become pregnant; in most cases the device has an effect like that of the morning-after pill--that is, it causes the expulsion of fertilized ovum from the uterus. An IUD can present serious problems, however. As a foreign body in the uterus, it creates irritation and inflammation and is associated with an increased incidence of pelvic inflammatory disease and subsequent infertility. Also perforation of the uterine wall by an IUD (although this rarely occurs) is a life-threatening situation.

Sterilization. Tubal ligation and vasectomy (cutting or cauterizing the uterine tubes or ductus deferentia, respectively) are surgical procedures that can be performed on an outpatient basis. They have failure rates of less than 1% and in no way diminish the sex drive. Patients are advised to consider these procedures irreversible, however. Although a successful reconnection can sometimes be achieved by microsurgical techniques, fertility is usually reduced substantially.

BARRIER METHODS

Spermicides, Diaphragms, and Cevical Caps. Spermicides are made of two basic components: a spermicidal (sperm-killing) chemical and harmless bulky base. The base is heavy enough to block the cervix, so even if some sperm cells aren't killed by the chemical, they are prevented from entering the cervical canal. Foams are the most effective spermicides--they spread quickly and coat the cervix evenly. Creams and jellies are more likely to fail because they don't spread as evenly throughout the cervix. Sponges--polyurethane discs soaked in spermicide--were once fairly popular, but they are no longer on the market. Spermicides are not highly effective when used alone; they are significantly more effective when used in conjunction with diaphragms, cervical caps, and condoms.

A diaphragm is a rubber or plastic dome with a flexible rim that fits over the cervix. It must be fit by a physician and should be used with spermicidal jelly or cream for maximum protection. A diaphragm should be left in place for at least 6 hours after sexual relations. Cervical caps, smaller version of the diaphragm, fit over the very end of the cervix. When used together with spermicides, they are as effective as full-sized diaphragms.

Condoms. A condom is a thin sheath made of rubber or animal membrane that is rolled onto the erect penis to receive the ejaculate, thus preventing spermatozoa from entering the vagina. Used with a spermicide, a condom is about 90% effective. An added benefit is the protection it affords against AIDS and other sexually transmitted disease. A female version is also available; it fits into the vagina and may also offer some protections against STDS.

A number of other methods of birth control are currently under investigation. These include reversible vaccines targeted against specific hormones involved in conception, such a hCG (human chorionic gonadotropin), LH, and FSH. Vaccines that target proteins on the surface of the sperm cell, or on the zona pellucida of the ovum, are also being studied. In addition, researchers are exploring the efficacy of agents that will inhibit sperm production in males, or render sperm cells incapable of fertilizing an ovum. At present, however, the only completely safe, 100% effective method continues to be abstinence--refraining from sexual intercourse. This form of birth control, particularly appropriate for many young people, warrants careful consideration.

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