BHIVA: How many children are born with HIV at a London hospital and why?

Since 1993 a total of 2% of pregnancies involving HIV-positive mothers have resulted in mother-to-child transmission of HIV at a large south London hospital, according to prospective data presented to the Twelfth Annual Conference of the British HIV Association in Brighton on March 31^st. The doctors, from King’s College Hospital, found that a significant proportion of transmissions occurred in the womb and suggest that this supports the earlier initiation of treatment to prevent mother-to-child transmission of HIV than currently recommended by the British HIV Association’s pregnancy guidelines.

Appropriate HIV treatment, mode of delivery and not breastfeeding can cut the risk of mother-to-child transmission of HIV from approximately 8% to less than 1%. To reflect this knowledge, guidelines on the prevention of mother-to-child HIV transmission were prepared by the British HIV Association in 2001 and revised in 2005. Nevertheless, mother-to-child transmission still occurs.

To understand the extent and reasons for HIV transmission, doctors at King’s College Hospital in Camberwell, south London conducted a prospective study, including all HIV-positive women seen at the hospital for antenatal care between 1993 and 2004.

During the eleven years of the study, a total of 296 pregnancies in 274 HIV-positive women received care at the hospital. Routine HIV testing during pregnancy revelaed the majority of these HIV infections (55%). A total of six pregnancies (2%) resulted in mother-to-child transmission of HIV.

The investigators looked at these six cases to find the reasons for HIV transmission. The first baby was born prematurely; the mother was diagnosed late during pregnancy (week 38) in the second case; failure to attend for follow-up was identified as the reason for transmission in the third case; coinfection with malaria and tuberculosis complicated the care of the fourth woman and is thought to have resulted in transmission of HIV to the infant; in the fifth case early infection in the womb is thought to have occurred, as antiretroviral therapy was started at week 27; and in the sixth case the mother experienced an HIV seroconversion illness during pregnancy.

Although the investigators believe that efforts made by a multi-disciplinary team to prevent mother-to-child transmission of HIV are working well, they express concern that four of the six transmissions seen at their centre occurred in the womb. The British HIV Association pregnancy guidelines suggest that women who are not already on HIV therapy for their own health should commence appropriate antiretroviral treatment (AZT monotherapy for women with a viral load below 10,000 copies/ml, combination antiretroviral therapy for those with a higher viral load) at the beginning of the third trimester of pregnancy, but the investigators suggest that treatment should be initiated between weeks 22 and 23 of pregnancy.