Antenatal HIV screening policies throughout the British Isles were sur
veyed and results linked to data on HIV-infected pregnant women notifi
ed through the Royal College of Obstetricians and Gynaecologists. Unit
s offering HIV testing to all pregnant women were compared with those
offering it only to women considered to be at risk, and in both situat
ions fewer than 50% of infected women were identified as HIV infected
for the first time in antenatal clinics. Based on laboratory reports o
f HIV infection in women of childbearing age, paediatric reports of ch
ildren born to HIV positive women and unlinked anonymous neonatal scre
ening programmes, there was evidence of under-recognition of HIV infec
tion in pregnancy, particularly in England and Wales.