HIV-negative women who use pre-exposure prophylaxis (PrEP) immediately prior to engaging in carefully timed sexual intercourse with their antiretroviral-treated HIV-positive male partners may further reduce their already low risk of being exposed to the virus. The encouraging data, reported Monday at the Fourth IAS Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2007) in Sydney, suggest that this may be a safe and effective option for serodiscordant couples hoping to have children by way of natural conception.

According to data sited by Peitro Vernazza, MD, the lead author of the study and a physician at Cantonal Hospital in St. Gallen, Switzerland, approximately half of all HIV-discordant couples express the desire to conceive a child. Some fertility clinics, including a few in the United States, offer “sperm washing” services to couples in which the male partner is HIV positive. However, the processing of semen, along with the required intrauterine insemination (IUI) or in vitro fertilization (IVF), can be prohibitively expensive and is only successful 40 percent to 70 percent of the time.

Dr. Vernazza and his colleagues note that approximately one third of discordant couples who contact fertility clinics for sperm washing and IUI or IFV do not start the procedure—and half go on to conceive naturally.

To explore the feasibility of reducing the risk of HIV transmission among HIV-positive men hoping to have children with their HIV-negative female partners, Dr. Vernazza’s group worked with 22 discordant couples at Cantonal Hospital.

The couples were counseled on methods to maximize the safety of unprotected sexual intercourse to achieve pregnancy. First was the recommendation that the HIV-positive male partner be on an effective antiretroviral regimen and have a viral load below 50 copies for at least three months prior to unprotected intercourse.

Upon entering the program, the male partner’s semen was tested for detectable HIV. Deferring sexual intercourse was recommended if the semen sample was positive for HV-RNA.

The HIV-negative female partner underwent urine-based luteinizing hormone (LH) testing to time ovulation and determine the optimal window for sexual intercourse. On the morning of peak urine LH, a standard 300 mg PrEP dose of Viread (tenofovir) was given, followed by a second dose 24 hours later. The couples were instructed to have sexual intercourse the evening after the second dose of PrEP.

Among the 22 couples followed by Dr. Vernazza’s group, 70 percent became pregnant. Fifty percent of the women became pregnant after up to three episodes of unprotected intercourse. No women became infected with HIV while participating in the program. 

Dr. Vernazza concluded that, given the minimum risk of HIV transmission if the male HIV-positive partner is on suppressive antiretroviral therapy, timed unprotected intercourse could be a reasonable alternative to in vitro methods. While the design of this informal study did not allow for an accurate assessment of Viread’s efficacy as PrEP—given its use in combination with other risk-reducing procedures—Dr. Vernazza reckoned that the use of prophylaxis to further reduce the minimal risk was “well accepted.”

These data build upon the encouraging results from other groups exploring the safety and effectiveness of natural conception among serodiscordant couples.