Efforts are under way to improve condoms, diaphragms and similar devices that work by providing a physical barrier between sperm and egg.
Research organizations, including FHI and the World Health Organization, and private industry are exploring the use of new materials for male condoms, such as polyurethane (plastic) instead of latex, and new designs, such as loose-fitting condoms instead of the snug fit currently used. The first plastic condom was introduced last year in Europe and the United States. Plastic condoms have several advantages, including possibly a longer shelf-life than the latex condom, possibly improved sensation during sexual intercourse, and compatibility with oil-based lubricants, which destroy latex.
The polyurethane female condom, which can be used for contraception and STD prevention, is being studied to determine whether it can be used more than once. Being able to clean the device and reuse it safely and effectively could lower the cost to users. Additional FHI studies to evaluate the method's acceptability, including male partners' attitudes, are under way in Mexico. New types of female condoms are being studied, including the Bikini Condom, which is worn like a panty, and another product called Women's Choice, which is inserted with an applicator.
The contraceptive sponge, which is not widely available in many countries, is undergoing refinements. A new sponge, Protectaid, is available in Canada. Made of polyurethane, the device contains F-5 gel, a combination of three spermicides (nonoxynol-9, benzalkonium chloride and sodium cholate) in low doses. Manufacturers believe these lower concentrations of spermicides will reduce irritation to the vaginal mucosa. A sponge containing benzalkonium chloride (BZK) is available in Europe. However, the Today sponge, which contains nonoxynol-9 (N-9) and was sold in the United States, is no longer manufactured.
The diaphragm has the advantage of being a female-controlled method that prevents pregnancy and appears to reduce the risks of some STDs, including gonorrhea and chlamydia, as well as pelvic inflammatory disease. Yet, many women find the device inconvenient, since it must be inserted prior to intercourse, and messy, since it must be used with a spermicide gel or cream. Researchers are exploring ways to make this device easier and more appealing to use.
In Brazil, women from three clinics participated in a study to compare contraceptive effectiveness of the diaphragm when used with spermicide during time of intercourse, and when not used with a spermicide but worn continuously. Spermicide use did not significantly improve effectiveness, researchers found, and the cost and messiness of spermicide may have discouraged correct use.1 Yet, because spermicides also act as microbicides, many researchers suggest that diaphragms without spermicide may offer little protection against STDs. A study in London found relatively high pregnancy rates, but promising continuation rates, among 110 women who continuously used a fit-free diaphragm (one that did not require fitting by a doctor) without spermicide. The 12-month accidental pregnancy rate was 24.1 pregnancies per 100 women.2
A new type of diaphragm -- one made of silicone rather than latex -- has been developed, and a study of this device's effectiveness and acceptability is now under way in Brazil. According to Dr. Carlos Petta of Centro de Pesquisas e Controle das Doenças Materno-Infantis de Campinas (CEMICAMP), the diaphragm, used without spermicide and worn continuously by women in the study, is removed only for washing. This diaphragm comes in different colors, which researchers think may be more attractive to women.
Another new method, Lea's Shield, is a cup-shaped barrier that covers the cervix. This device has a valve that allows the draining of cervical secretions and menstrual flow, and has a U-shaped loop for easy removal. Made of silicone rubber, it can be worn up to 48 hours. The U.S.-based Contraceptive Development and Research program (CONRAD) has conducted safety and efficacy studies of this device, which eventually may be available without a visit to a health provider.
The Gynaeseal diaphragm tampon, available in Australia, has an inner chamber and an outer pouch. The inner chamber has a one-way valve that allows menstrual fluids to pass through, and cervical secretions are collected in the outer pouch.
Cervical caps, available primarily in the United States and Europe, also are being refined. Shaped like a small dome, the cap is used with spermicide and can be inserted 40 hours prior to intercourse, and must not be removed for at least eight hours following intercourse. Side effects include vaginal odor and discharge, vaginal tears and cervical irritation. Also, some cervical cap users report increased rates of urinary tract infections, as do diaphragm users.
The safety and efficacy of a new type of cervical cap are being evaluated in the United States by FHI and CONRAD. Femcap, which is made of silicone rubber, is a device shaped like a hat with a wide, upturned brim. It fits over the cervix, is designed to be worn for up to 48 hours, and may be effective without spermicide.
-- Barbara Barnett
Footnotes
- Ferreira AE, Araújo MJ, Regina CH, et al. Effectiveness of the diaphragm, used continuously, without spermicide. Contraception 1993; 48(1): 29-35.
- Smith C, Garr G, Feldblum PJ, et al. Effectiveness of the non-spermicidal fit-free diaphragm. Contraception 1995; 51:289-91.
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