seriouscomplication is slight. In the 1980s sterilizationbecame the preferred method among U.S. couplesdesiring no further children. The most optimisticprospects for reversing sterilization for women andmen exists when there is the least damage to theirtubes at the time of sterilization. It is estimated thatas many as 60 percent of reversals are successful(success is measured by a pregnancy). Manyindividuals, however, may not even be candidatesfor an attempt at reversal, especially women whohave undergone electrocauterization or surgicalcutting of their tubes. New or ExperimentalContraceptives Several new drugs andcontraceptive devices are at present undergoingexamination in the United States. Thus an injectionof the synthetic progesterone Depo-Provera(currently used in more than 90 countries)prevents ovulation for three months. Animal tests,however, suggest that the drug may induce somecancers, and have other undesirable side-effects.Also in use in several countries is a capsule,implanted beneath the skin of the upper arm, thatslowly releases the synthetic hormonelevonorgestrel over a period of five years. Thecapsule, which was approved by the WorldHealth Organization in 1985 for distribution byUnited Nations agencies, has minimal known sideeffects but should not be used by women whohave liver disease or breast cancer. Anothercontraceptive approach, successful in animals andcurrently undergoing human trials, is vaccination.One vaccine delivers antibodies against a hormonethat plays a crucial role in pregnancy. A secondworks against a hormone in the matrix surroundingthe egg, blocking sperm from penetrating. Maleand unisex oral contraceptives are currently inresearch. SOCIAL ISSUES Birth control, orlimiting reproduction, has become an issue ofmajor importance in the contemporary worldbecause of the problems posed byPOPULATION growth. Until relatively recently,however, most cultures have stressed increasing,rather than reducing, procrea...
