As global concern about HIV and other STI has grown, decisions on contraceptive use have increasingly involved the need to prevent infections of the genital tract. The use of contraception has two potential benefits: (1) the prevention of unplanned pregnancy; and (2) protection against STI1. Abstinence from penile–vaginal intercourse provides nearly absolute protection against both outcomes. For individuals choosing to be sexually active, contraception reduces, but does not eliminate, the risk of unintended pregnancy. Unfortunately, the contraceptives with the best record of pregnancy prevention provide minimal protection against STI (including HIV). This brief article addresses the role of non-hormonal contraception and HIV acquisition.
Both published and unpublished literature examining the association of non-hormonal contraception and HIV acquisition were reviewed. The quality of different studies was assessed according to the US Preventive Services Task Force criteria. The greatest weight in deriving inferences from these studies was based on level 1 evidence. Recent conclusions from consensus conferences examining bodies of data were also factored in.
Because of ethical implications, most studies used observational (level 2) designs. These studies are limited in their methodological quality, including an ascertainment of exposure to HIV, an ascertainment of contraceptive use, laboratory measures of HIV, and statistical analytical approaches to determining risk.
If men are willing and educated to use them properly, male condoms protect against the transmission of HIV by preventing direct contact with semen, genital discharge, and other infectious secretions2,3. To be effective, condoms must be applied before genital contact, must remain intact, and most importantly, must be used consistently and correctly with each active intercourse.
Many prospective studies over the past decade have evaluated the impact of male condoms in protecting against HIV (Figure 1). The data are remarkably supportive, all showing a protective effect1,2. The regular use of male condoms reduces the risk of acquiring or transmitting HIV. In the most definitive examples, the European and Haitian studies of HIV-discordant couples found that individuals who reported consistent condom use had minimal or no HIV transmission after many years of observation.
Although data are sparse, the female condom should also protect against HIV under similar circumstances as the male condom. Female condoms have been shown to provide in-vivo protection against HIV. The consistent use of female condoms significantly protected against recurring trichomonal infection4. In Thailand, sex workers randomly assigned to a group receiving female condoms as a back-up to male condoms had fewer unprotected coital acts and lower STI rates than individuals receiving male condoms only5.
Diaphragms and Other Physical Cervical Barriers
The primary anatomical sites for sexual transmission of HIV are unclear; however, clinical data support the relative importance of covering the cervical rather than the vaginal epithelium. Many of the receptors known to attract HIV (including CCR5 and CXCR4) are concentrated on the cervix6. In addition, the cervix produces immunological substances that may help protect against some pathogens, including HIV. Therefore, current research is examining the additional effect, if any, which diaphragms and other cervical barriers could have in protecting against HIV7.
Spermicides containing nonoxynol-9 do not provide any protection against HIV, regardless of the formulation or dosage8,9. The best data evaluating nonoxynol-9 come from well-performed RCT. To date, four RCT have compared three different formulations containing nonoxynol-9 – a gel, a sponge, and the film. Taken together, these studies show that nonoxynol-9 spermicide used alone does not protect against HIV (Figure 2). This finding has accelerated the pace of research for alternative microbicides that are both safe and effective8.
Our current data are inconsistent as to whether IUD use affects the risk of HIV acquisition (Figure 3). Of the nine observational studies examining the association between IUD use and HIV acquisition, the data were equally divided10 – only two studies reached statistical significance (one showing harm, one showing protection). This implies that whereas IUD provide no protection against HIV, they do not carry any greater risk of acquiring HIV than if no contraceptive methods were used11.
Data on combination contraceptive approaches indicate a trade-off between contraceptive effectiveness and the percentage reporting consistent condom use as a dual method12. Under typical conditions of inconsistent use, condoms provide moderate protection against both pregnancy and STI. When used perfectly (consistently and correctly), condoms provide good protection against both pregnancy and HIV. Given the lack of an ideal method to achieve both objectives, clinicians and their clients need to consider the woman's stage of life, her sexual behavioral patterns, and her childbearing plans when discussing optimum contraceptive choices.
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