HIV in pregnant women in UK: still failing to meet diagnosis targets

The latest figures from the Health Protection Agency show that during the first six months of 2002, England as a whole was still failing to reach government set targets to diagnose 80% of HIV infections in pregnant women prior to delivery.

National unlinked anonymous (UA) monitoring of the prevalence of HIV infection in pregnant women, by testing for maternal antibody in infant dried blood spots, began in the UK in 1988. Since 1992, the survey has covered approximately 70% of UK births. The results of UA monitoring are aligned with reports of HIV infected pregnant women made through the Royal College of Obstetricians and Gynaecologists (RCOG) to the National Study of HIV in Pregnancy and Childhood (NSHPC). This provides the best estimates of the proportions of HIV-positive pregnant women who have had their infection diagnosed prior to pregnancy or during current antenatal care.

In 1994 it became apparent that interventions implemented during pregnancy and in the perinatal period can reduce the risk of transmission of HIV from mother-to-child from one in four to less than one in 50, and the uptake of such interventions by diagnosed HIV-positive pregnant women in the UK is high. There are also direct benefits to the woman’s own health from having her HIV infection diagnosed earlier than might otherwise have happened.

Outside London, the prevalence of HIV infection among women giving birth has remained consistently low. Prevalence in the rest of England for the first half of 2002 is estimated to be 3.5/10,000, and in Scotland 4.8/10,000 women.

National targets and the proportion of maternal infections diagnosed?

In 1999, national targets that offer and recommend HIV testing to all pregnant women throughout England were established by the Department of Health. It was intended that by increasing the uptake of antenatal HIV testing to 90%, and by increasing the proportion of HIV infections diagnosed prior to delivery to 80%, an 80% reduction in the proportion of children acquiring HIV infection from their mothers should be achieved by December 2002.

In London, up to the end of June 2002, 135 diagnosed maternal infections had been reported to the NSHPC by the end of the year, giving a minimum overall detection rate of 66% (135/205) and an antenatal detection rate of 53%. The data for the rest of England in the first half of 2002 show an overall detection rate of 81% (57/70), meeting the Department of Health target for the first time.

For Scotland, data show that at least 67% (8/12) of maternal HIV infections were diagnosed before delivery in the first half of 2002. The equivalent overall detection rates in the same period of 2001 for London, the rest of England, and Scotland were 73%, 33% and 75% respectively.

These interim half-year data are, however, subject to reporting delay and the estimated proportion of infections diagnosed is expected to rise further as late reports are received. In 2001, it can be estimated that there were about 560 births to HIV-positive women in the UK. Assuming a transmission rate of about 25% for undiagnosed women, and 2% for diagnosed women (allowing for late diagnoses and a small proportion of diagnosed women declining interventions, about 50 infants would have acquired HIV infection from their mothers. Continued improvements in detection rates before delivery have resulted in a decreasing proportion of HIV-positive women passing HIV infection on to their child and, despite an increase in the number of HIV-positive women giving birth, the number of maternally- acquired HIV infections was probably similar in 2001 to 2000.