Sounds simple enough. And in many, cases it is. Barrier methods like the condom or diaphragm, which keep sperm from meeting egg, can be 88 percent effective. The pill suppresses ovulation, leaving no egg for sperm to encounter; it can be 95 percent effective. Vasectomies for men and sterilizations for women are foolproof. But barriers require forethought, the pill has side effects such as nausea and a possible increased risk of breast cancer, and sterilization is permanent. Unfortunately, nothing else loomed on the horizon because drug companies, worried about mounting liability suits, stopped contraceptive research in the 1980s.
But the logjam may be breaking. Last year the Food and Drug Administration approved Depo-Provera, an injection of the synthetic hormone progestogen: taken once every three months, it prevents ovulation. Norplant works the same way, except that its progestogen is released more slowly, with fewer side effects. Last year, too, a “female condom” neared FDA approval: it blocks the cervix and frees women from depending on a man for last-minute contraception. President Bill Clinton did his part for family planning on his third day in office, directing the FDA to review the safety and efficacy of the so-called French abortion pill, RU 486: taken within seven weeks of intercourse, its antiprogestins lock up the hormone needed to keep a fertilized egg implanted. Researchers hope Clinton’s action will spur the French manufacturer to request FDA approval for RU 486.
In the absence of new offerings from the drug companies, college women are discovering their own “morning-after pill.” Two tablets of a standard birth-control pill, Ovral, taken within 72 hours of intercourse, plus two more pills half a day later, bring on a menstrual period. Low-dose pills work, too, with slightly different dose regimens. Both can cause intense nausea. But no manufacturer has applied for FDA approval to use the drug as a morning-after pill, so it cannot be dispensed at clinics using federal funds. Even many gynecologists claim to be unaware of it.
Better methods are poised at the frontiers of contraception. Some of the most innovative are directed at men. This spring, Rosemary Thau of the Population Council will begin clinical trials of an injection that blocks the gonadotropin-releasing hormone. GnRH regulates the production of sperm. The shot, when paired with another hormone that maintains libido, could make men infertile but not uninterested. One drawback: men would require the injections every day. “Jabbing even once a week is sheer nonsense,” says Dr. Gabriel Bialy of the National Institute of Child Health and Human Development. But it might be possible to up the dosage and so decrease how often a shot is required.
Instant spermicide cocktails are also in the works. Called imidazoles, they are currently used to-treat fungal and vaginal infections. But in tests on lab animals these compounds also entered male reproductive glands and mixed with the ejaculate to kill sperm. If it works on people, it could be at least as effective as a condom and cause a lot less fumbling. Another sperm-slayer is based on a native Chinese herbal remedy called Tripterigium wilfordii. Men who continuously take extracts of this herb become infertile. Although scientists haven’t run any U.S. clinical trials yet, they suspect the infertility wears off soon after the man stops taking the tablets. It could be the male pill.
Further on the horizon are vaccines against pregnancy. A woman could be immunized against the hormone human chorionic gonadotropin (hCG), which keeps the uterine lining from being sloughed off. The Population Council has studied it in clinical trials in India and Australia-and is set to start a larger trial in Sweden to see if vaccinated women make sufficient antibodies against hCG to expel a fertilized egg. Or, a vaccine could target a woman’s own unfertilized eggs. Bonnie Dunbar of Baylor College of Medicine is working on one that would attack the layer of proteins that coat an egg. If antibodies can be stimulated, and if they glom onto the proteins, they might form a barrier to sperm. Another idea is to vaccinate women against sperm: 5 to 10 percent of infertile women have antibodies that surround and immobilize sperm. A sperm vaccine would be long-acting but reversible, and wouldn’t tinker with a woman’s hormones. It can take about two decades to get a new contraceptive from lab to market, so don’t expect to get vaccinated against sperm tomorrow. But finally it looks as if science and politics may unite to provide more options for preventing pregnancy.
