Use of pre-exposure prophylaxis (PrEP) by sero-different couples wanting to conceive a child

Simon Collins, HIV i-Base

Few couples have access to, or can afford, spermwashing, which although associated with effective protection from HIV transmission to a negative partner, also has a low conception rate. Higher rates of successful pregnancies have been reported in sero-different couples (where the man is HIV-positive and the woman is HIV-negative), from limited conception attempts, also without transmission, in the context of undetectable viral load.

Pietro Vernazza and colleagues from Cantonal Hospital St. Gallen, Switzerland presented results from an intervention designed to reduce risk-taking behaviour in 22 HIV-different couples wanting to conceive a child.

All male partners had been on antiretroviral treatment with suppressed viral load (<50 copies/mL) for at least three months. Seminal viral load was undetectable in all men (though only tested at the start of the study). This included urine LH-peak measurement to determine ovulation and pre-exposure prophylaxis with tenofovir 36 and 12 hours before intercourse.

Twenty-one couples (6 of whom had already used unprotected intercourse) decided to use the proposed risk reduction strategy with timed intercourse and TDF Pre-Exposure-Prophylaxis. Pregnancy rates were high with more than 50% pregnancies achieved after 3 cycles (11/21) and 70% women (15/21) became pregnant after up to 10 attempts. All women tested negative for HIV-antibodies 3 months after the last exposure.

The researchers concluded that the number of HIV-different couples who practice unprotected sex to conceive is likely to be underestimated. The risk of transmission in a couple with a fully treated male partner is low and can further be reduced by timed intercourse and a short pre-exposure prophylaxis with tenofovir. They also reported that the pregnancy rates of natural conception in this study were substantially higher than by artificial reproduction techniques, which were around 40% in their clinic programme.


Data from animal studies suggest that using a single ARV dose after exposure as post-exposure prophylaxis (PEP) and PrEP could offer additional benefit. Recent macaque studies have indicated that use of tenofovir and FTC would provide additional benefit to tenofovir monotherapy, and would reduce any risk of resistance, in the rare event that infection occurred. [3]

An oral presentation at the Glasgow conference in 2004 included results from 75 pregnancies in sero-different couples who had successful conceived using this approach, also with no HIV transmission to the negative partner. [2]

However, as per-risk exposure with an undetectable viral load is estimated in one in several thousand, the numbers in these studies are still far too low to comment either way on the safety in terms of HIV transmission. or the reduction in relative risk from any f the specific interventions such as PrEP.

However, given the difficulties associated with sperm-washing, including access, cost and low conception rate, and the importance for many couples to have children, this approach deserves wider recognition and debate.

An important caution is clearly that while these risks are likely to be extremely low for limited conception attempts, the risk would increase if the couple did not return to safer sex afterwards.


  1. Vernazza P, Brenner I, Graf I. Pre-exposure prophylaxis and timed intercourse for HIV-discordant couples willing to conceive a child. 4th IAS conference, Sydney, 2007. Abstract MoPDC01.
  2. 2. Barreiro P et al. Benefit of therapy for serodiscordant couples willing to be parents. 7th Intl Congress on HIV Therapy, 14-18 November 2004, Glasgow. Abstract PL13.3.
  3. 3. Garcia-Lerma JG, Otten R, Cong M et al. Intermittent antiretroviral prophylaxis with tenofovir and emtricitabine protects macaques against repeated rectal SHIV exposures. Antiviral therapy 2007; 12:S96. Abstract 85. See July issue of HTB:

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