Protecting the Cervix for Pregnancy and Disease Prevention

Photo courtesy of CBAS

While use of barrier methods can be traced back to ancient times, cervical caps and diaphragms were first manufactured and marketed for pregnancy prevention in the mid 19th century. Cervical barriers are latex or silicone cups that fit at the upper end of the vaginal tract, covering the cervix.

There are seven FDA-approved cervical barrier methods in the United States, including 4 diaphragms, 2 cervical caps, and the female condom, yet only a small percentage of women who use contraceptives use these products. When used correctly and consistently with spermicides, cervical barriers are 74-95% effective against pregnancy. They are safe and have very few side effects.

Many experts now believe that in addition to providing contraceptive benefits, cervical barriers may help protect against STIs, including HIV. This hypothesis is based on a growing body of evidence suggesting the cervix is the "hot spot" for disease transmission and that protecting the cervix may reduce the risk of infection.

Why the cervix is the "hot spot" for disease transmission:

• Only one layer of cells cover most of the cervix; it is therefore more vulnerable to pathogens and disease than the lining of the vagina, which is 30-40 cell layers thick;
• STD pathogens preferentially infect the at the site of the cervix;
• HIV receptor cells are concentrated in the cervix and the upper genital tract (uterus, fallopian tubes, and ovaries); and
• The cervix is gateway to upper genital tract and the uterus – covering the cervix would also protect these areas.

The Current Research Agenda

The limited available evidence suggests that diaphragm use lowers the risk of STI infection (including chlamydia, gonorrhea, and pelvic inflammatory disease), but all studies to date have been observational. Rigorous research is currently underway to test this hypothesis and to rule out confounding factors, such as sexual behaviors of diaphragm users and the role of spermicides, which are usually used in conjunction with barrier methods.

Clinical trials in the U.S. and developing countries are currently underway to assess the safety and effectiveness of the diaphragm in reducing STI and HIV infection among women. A randomized controlled study (called the MIRA trial) of 4,500 women in South Africa and Zimbabwe is evaluating the effectiveness and acceptability of the diaphragm as an HIV/STI prevention method. Some studies are focusing on diaphragm use to prevent STIs such as chlamydia and gonorrhea. Other studies are exploring the use of barrier method together with microbicides and combination products.

Research into the topic of diaphragm acceptability has been conducted around the world. Studies in the United States and in developing countries such as Columbia, Turkey, Philippines, Brazil, and India have shown that many women find the diaphragm to be an acceptable contraceptive method. A very recent study in Zimbabwe showed that, if proven effective against HIV/STIs, the diaphragm used alone or in combination with a microbicide could provide an acceptable alternative to male condoms in at-risk Zimbabwean women.

Researchers are also considering the promise of barrier methods as desirable contraceptive options for HIV-positive or at-risk women. With some evidence suggesting a potential link between hormonal contraceptives and HIV infection, experts in family planning and HIV are eager to identify strategies to address and integrate pregnancy prevention and fertility management with HIV/AIDS care.

New Product Development

FemCap Photo courtesy of CBAS

Researchers and product developers are exploring new devices and techniques to make barrier methods easier and more convenient for women to use. One approach is to eliminate or minimize clinician fitting by developing a sizing guide that does not require a physical exam. The recently available FemCap accomplishes this by offering women three sizes, based on pregnancy and birthing history. Another cervical barrier, Lea's Shield, is one-size-fits-all. Some experts believe that a one-size-fits-all cervical barrier may fit the criteria for a future over-the-counter product. Other research, however, shows that the fitting process increases women’s confidence in their ability to use the method correctly.

Lea's Shield Photo courtesy of CBAS

Other products under development to improve cervical barrier methods include devices with easy-to-access removal straps, non-latex female condoms, disposable cervical caps and diaphragms, and cervical caps pre-filled with a microbicide product.