Spanish find that serodiscordant couples having unprotected sex to conceive - no cases of HIV transmission

Derek Thaczuk
Published: 15 November 2006

Spanish researchers have found that many heterosexual couples have successfully conceived children through natural means (i.e. unprotected intercourse) without transmitting HIV to the uninfected partner.

This study, published in the November 1st issue of the Journal of Acquired Immune Deficiency Syndromes, looked at 62 mixed-status couples (those in which one partner was HIV-positive and the other HIV-negative) who achieved ‘natural pregnancies’ through unprotected intercourse. All of the HIV-positive people in this study (whether male or female) were on antiretroviral therapy; all had undetectable viral loads.

The study found that none of the HIV-negative partners became HIV-infected, despite having had unprotected sex with their partner at least once. However, several of the babies died before birth, and one died from HIV complications shortly after.

Pregnancy and HIV risk

HIV infection in itself is not considered a reason to avoid pregnancy – at least, if effective antiretroviral treatment is available, as it is in the developed world. Current treatment guidelines can reduce the risk of passing HIV from an HIV-positive mother to her child to the range of 1% to 2%. Therefore, many mixed-status heterosexual couples are considering pregnancy.

To avoid infecting the HIV-negative partner, artificial insemination or other ‘assisted’ methods are safest. In the case where the male partner is HIV-negative and the woman HIV-positive, artificial insemination can completely eliminate the risk of infecting the male partner. In the case where the woman is HIV-negative and the man is positive, ‘sperm washing’ techniques are being investigated for achieving pregnancy safely.

However, there are couples who want to conceive by ‘natural’ rather than assisted means. There has not been a great deal of research on natural pregnancies in mixed-status couples. A study of HIV-negative women with HIV-positive partners, published in the Lancet in 1997, found that 4% of the women became HIV-positive some time after a natural pregnancy. However, not all of their partners were on antiretroviral therapy, and there was no information about viral load levels.

The Spanish study

The researchers in this recent study believe that theirs is “the first report describing the outcome of natural pregnancies in HIV-serodiscordant [i.e., mixed-status] couples in which the HIV-infected partner is receiving maximally suppressive HAART [i.e, has an undetectable viral load].” The study looked at all natural pregnancies achieved by mixed-status couples at three clinics in Spain, between 1998 and 2005: a total of 76 conceptions among 62 couples.

In all cases, the HIV-positive partner (40 of the men and 22 of the women) was on antiretroviral therapy, with an undetectable viral load (less than 50 copies/ml). (For the women, this was true at the time of conception, and throughout the pregnancy.) None of the 66 HIV-negative partners became infected with HIV, as confirmed by tests after conception and six months or more after delivery.

However, in the 30 pregnancies among HIV-positive women, there were seven premature fetal deaths – a rate of 23%, compared to 5% among the HIV-negative women. The researchers point out that “conflicting data exist regarding the influence of HAART on obstetric outcomes”. Other recent studies have also found higher rates of fetal death in pregnant women on antiretroviral treatment,

Out of the 23 pregnancies that were carried to term in the HIV-positive women, one (4%) of the babies was born HIV-infected, even though the mother’s viral load was measured as undetectable at five separate clinic visits before delivery. (Caesarian delivery, which would lower the risk of transmission, was not used – the child was delivered naturally.) The child died of Pneumocystis jiroveci pneumonia in its third week.

The researchers stress that this was a retrospective study, which only looked at couples who achieved pregnancies, not at those who merely tried. Nor did know how many times each couple had had unprotected sex. Therefore, they could not draw any conclusions about the overall risk of HIV transmission for mixed-status couples. The researchers state that the “main conclusion that we can draw … is that HIV-discordant couples seeking pregnancy should receive specialized medical counseling and evaluation”, but that given further research, it may become possible “to validate natural conception as an acceptable option for HIV-discordant couples.”


Barreiro P et al. Natural pregnancies in HIV-serodiscordant couples receiving successful antiretroviral therapy. J Acquir Immune Defic Syndr. 43(3): 324-326, 2006.

Mandelbrot L et al. Natural conception in HIV-negative women with HIV-infected partners. Lancet 349: 850-851, 1997.

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