Abstract
OBJECTIVE: To assess the impact of the antenatal HIV screening programme in Norway in preventing HIV infection in children. SETTING: Norway, 1987–99. METHODS: In a simulated retrospective cohort design data were used from the mandatory HIV surveillance system to compare the observed number of children born infected with HIV in Norway 1987–99 to the expected number without the antenatal screening programme. The main measures were relative and absolute performance of the screening programme. Other measures were uptake and false positive rate of screening, and number and exposure category of screen positive women. RESULTS: 96% of 961 000 eligible pregnant women were tested. 0.1% had an indeterminate test result and 46 women (5.0/100 000) were confirmed screen positive. 27 were African or south east Asian women infected before immigration to Norway. Nine out of 739 000 live born children (1.2/100 000) were infected compared with the expected 18 with no screening. The absolute impact of the screening programme was 1.3 (95% confidence interval (95% CI) -0.1 to 2.7) prevented infections in 100 000 women screened. The relative preventive impact was 51% (-15% to 81%). CONCLUSIONS: The limited absolute impact is because of the very low prevalence of undetected HIV infection among pregnant women in Norway.