More than one in seven pregnancies in east London still poses transmission risk

During the last two years nearly half of HIV-positive pregnant women at one east London hospital have given birth with a viral load over 50, and over one in seven with a viral load over 1000, a poster presentation at the Eighth Glasgow International Congress on Drug Therapy in HIV Infection revealed last week.

The presenters from the Greenway HIV Clinic at Newham University Hospital comment that “the number of women delivering with a detectable viral load is a concern”.

They attribute failure to achieve undetectable viral loads in the mother and minimise the HIV risk to the baby in part to late presentation and “the difficult socio-economic conditions many of these women experience.”

There were 95 pregnancies in 84 women attending the Greenway Centre between March 2004 and March 2006, resulting in 88 live births, four miscarriages and three terminations. Of the women, 87% were from sub-Saharan Africa.

Fifty-sex per cent of women knew they had HIV before they conceived, 41% did not and in 3% of cases it is not known if they knew. Of the women who knew they had HIV, half were already taking antiretroviral treatment.

Three-quarters of the women who were unaware of their HIV status were diagnosed in the second trimester (months three to six) of pregnancy and most of the rest in the third trimester but one was found to have HIV during labour, one did not volunteer her HIV status to the obstetrician despite being a Greenway patient, and in at least two other cases medical records are unclear about whether the women’s status was known.

One-third of newly-diagnosed patients and nearly half of diagnosed patients took AZT monotherapy to prevent mother-to-child transmission, but this became a much less favoured treatment option over time. Of 59 women where the antiretroviral regimen was known, over half had AZT monotherapy in 2004 but only one (7.7%) had it in 2006. By 2006 the predominant ARV regime taken was protease-inhibitor-based HAART; this was given to a quarter of women in 2004 but two-thirds of women in 2006. Non-nucleoside-based regimens increased slightly from 20% to 30% of the total treatments.

Although the BHIVA pregnancy guidelines (published 2005) say that elective caesarean delivery is no longer necessary and vaginal delivery can be used with reasonable precautions, caesareans continued to be the primary mode of delivery. Elective and emergency caesareans declined from 91% of deliveries in 2004 to 75% of deliveries in 2006.

The maternal HIV viral load at delivery was available for 73 out of 88 live births. The mother’s viral load was over 50 in 34 of these (47%) and over 1000 in 10 of these (14% or over one in seven).

Intravenous AZT was given to these women during delivery, although as the authors point out there is no data on the efficacy of this in reducing mother-to-child transmission.

Of the 34 mothers with viral loads over 50, five had vaginal delivery, eight emergency caesareans and 21 elective caesareans; 22 had intravenous AZT, two did not and no AZT information was available for the other eight.

Of the subset of 10 mothers with viral loads over 1000, all but one had caesareans (five emergency and four elective), six had intravenous AZT, one did not and no AZT information was available for the other three. One woman was diagnosed at the onset of labour and one presented in premature labour at 24 weeks and did not tell A&E staff she had HIV.

Why did so many women have detectable HIV at the time they gave birth? The authors suggest three reasons. Firstly, it takes longer to suppress HIV with protease-inhibitor-based regimens than with NNRTIs; secondly, with increased use of HAART there has also come an increased incidence of premature labour and hence of emergency caesareans and unplanned vaginal deliveries; and thirdly many women book into antenatal care very late and are therefore diagnosed very late, in part, the authors imply, due to fears about being entitled to care in the United Kingdom.