New Developments in Vaginal Contraception
This review on new developments in vaginal contraception examines the history and usage of vaginal methods, assesses the effectiveness, proper use, and safety of spermicides, contraceptive sponges, diaphragms, and cervical caps, discusses the disease prevention effects of vaginal methods, and explores some program issues. The female vaginal methods are less effective than oral contraceptives, IUDs, or voluntary sterilization, and may entail high risks of accidental pregnancy, especially among women who are not conscientious users. Although they have almost no side effects, they may be awkward to use. They provide some protection against sexually transmitted diseases. Spermicides are increasingly available throughout the world and require no prescription. They come as jellies, creams, foams, foaming tablets or suppositories, melting suppositories, or soluble film. They contain different spermicidal ingredients, of which nonoxynol-9, octoxynol-9, and menfegol are the most common. Evaluation studies show that 1-30% of spermicide users become pregnant in each year of use, but careful and consistent users have low pregnancy rates. A few US studies which raised the possibility that spermicide use in early pregnancy might cause congenital defects have been criticized on technical grounds and their findings have not been confirmed. The new contraceptive sponge "Today", manufactured by the VLI Corporation, is made of polyurethane and impregnated with nonoxynol-9. The sponge is assumed to work by releasing spermicide, absorbing semen, and blocking the cervical opening. It can be kept in place for 24 hours, is less messy than other vaginal methods, and can be sold over-the-counter. 9-27% of users became pregnant in the 1st year of use in international trials. There is little evidence concerning longterm safety or infection. Diaphragms come in 3 major designs, flat spring, coil-spring, and arcing, which make it possible to fit anatomically dissimilar women. Careful instruction in insertion and use are necessary for new users. Failure rates of 2-23%/year have been reported. Cervical caps are held in place over the cervix by suction and must be carefully fitted. 1st year failure rates range from 8-20%. Many women have difficulty using caps because of fitting problems or because of difficulty of insertion and removal. Other disadvantages include possible dislodgement during sex, odor, and possible vaginal laceration with 1 type of cap. The future prospects of vaginal methods in developing countries are uncertain because of their high cost and low effectiveness relative to other methods.