Infertility
In some cases, couples do not need to prevent pregnancy; instead, conception, or fertilization, does not occur despite frequent intercourse. The American Medical Association estimates that 15% of all U.S. couples are unable to have children and therefore are termed sterile; another 10% have fewer children than they wish and therefore are termed infertile. The latter term assumes that the couple has been trying to become pregnant and has been unsuccessful for at least one year.
Causes of Infertility
The two major causes of female infertility are (1) blocked uterine tubes, possibly due to a previous infection, particularly gonorrhea or chlamydia; and (2) failure to ovulate due to low body weight. Endometriosis can also contribute to infertility.
In some cases, the causes of infertility can be corrected surgically and/or medically If no obstruction is apparent and body weight is normaL females can be given a substance rich in FSH and LH extracted from the urine of postmenopausal women. This treatment causes multiple ovulations and, sometimes, multiple pregnancies.
The most frequent causes of male infertility are low sperm count and/or a large proportion of abnormal sperm. Disease, radiation, chemical mutagens, high testes temperature, and the use of psychoactive drugs can contribute to infertility.
When reproduction does not occur in the usual manner, many couples adopt a child. Other couples try one of the alternative reproductive methods.
Corrective medical and surgical procedures can help people vvho are infertile but vvish to have a child. Altemative methods of reproduction may also be considered.
Birth Control
The most reliable method of birth control is abstinencethat is, the absence of sexual intercourse. This form of birth control has the added advantage of preventing sexually transmitted diseases.
In the male, a vasectomy consists of cutting and sealing the vas deferens on each side so that the sperm are unable to reach the seminal fluid that is ejected at the time of orgasm. The sperm are then largely reabsorbed. Following this operation, which can be done in a doctor's office, the amount of ejaculate remains normal because sperm account for only about 1 % of semen volume. Also, the secondary sexual characteristics are not affected, since the testes continue to produce testosterone.
In the female, tubal ligation consists of cutting and sealing the uterine tubes. Pregnancy rarely occurs because the passage of the egg through the uterine tubes has been blocked. Whereas major abdominal surgery was formerly required for a tubal ligation, today simpler procedures are available. Using a method called laparoscopy, which requires only two small incisions, the surgeon inserts a small, lit telescope to view the uterine tubes and a small surgical blade to sever them. An even newer method called hysteroscopy (histah-r6'sko-pe) uses a telescope within the uterus to seal the tubes by means of an electrical current.
There has been a revival of interest in barrier methods of birth control, including male and female condoms, because these methods offer some protection against sexually transmitted diseases. The female condom is essentially a large polyurethane tube with a closed end that fits over the cervix and an open end that covers the external genitals.
Investigators have long searched for a "male pill." Analogs of gonadotropic-releasing hormone have been used to prevent the hypothalamus from stimulating the anterior pituitary. Inhibin has also been used to prevent the anterior pituitary from producing FSH. Testosterone and/or related chemicals have been used to inhibit spermatogenesis in males, but feminizing side effects are common because the body changes an excess of testosterone to estrogen.
Contraceptive vaccines are now being developed. For example, a vaccine developed to immunize women against HCG, the hormone so necessary to implantation of the embryo, was successful in a limited clinical trial. Since HCG is not normally present in the body, no untoward autoimmunity reaction is expected, and the immunization does wear off with time. Others believe that it would also be possible to develop a safe antisperm vaccine that would be used in women.
Morning-After Pills
Morning-after regimens are available that, depending on when the woman begins medication, either prevent fertilization altogether or stop the fertilized egg from ever implanting. These regimens involve taking pills containing synthetic progesterone and/or estrogen in a manner prescribed by a physician. Many women do not realize that this method of birth control is available, and yet use of these regimens could greatly reduce the number of unintended pregnancies. Effective treatment sometimes causes nausea and vomiting, which can be severe.
Mifepristone, better known as RU486, is a pill presently used in France and Great Britain that is now being considered for use in the United States. RU486 causes the loss of an implanted embryo by blocking the progesterone receptors of endometrial cells. Without functioning receptors for progesterone, the endometrium sloughs off, carrying the embryo with it. When taken in conjunction with a prostaglandin to induce uterine contractions, RU486 is 95% effective. Someday, the medication may be used by women who are experiencing delayed menstruation without knowing if they are actually pregnant.
Numerous. well-known birth control methods and devices are available to people who want to prevent pregnancy. but their effectiveness varies. In addition. new methods are being developed.
