To describe the patterns of screening for hepatitis C virus (HCV) infection in methadone-maintained pregnant women and their infants.

Retrospective review of medical records from one rural and two metropolitan hospitals in New South Wales for pregnant women on methadone maintenance treatment and infants born to these women between 1 January 2000 and 31 December 2006, as well as records for pregnant women who were not on methadone treatment.

Rates of anti-HCV antibody and HCV RNA testing for pregnant women and their infants, and ages at which infants attended follow-up appointments.

Of 295 pregnant women on methadone maintenance treatment, 288 were tested for anti-HCV antibodies (98%), compared with 1995 of 9987 women who were not on methadone treatment (20%) (P < 0.001). Seropositive results were obtained for 243 women in the methadone group (84%) and 54 in the non-methadone group (3%) (P < 0.001), of whom 44 (18%) and 17 (31%), respectively, were subsequently tested for HCV RNA (P = 0.03). HCV RNA test results were positive for 31 (70%) and 10 (59%) seropositive women in the methadone and non-methadone groups, respectively (P = 0.39). Of infants of HCV-seropositive methadone-maintained mothers, 27% of those for whom we had follow-up attendance data received HCV screening, and one of these infants tested positive for anti-HCV antibodies and HCV RNA.

Screening for HCV infection in the high-risk population of pregnant women on methadone maintenance treatment and their infants is inadequate. This could lead to significant underdetection of active HCV infection in this high-risk population, and their infants. Current screening guidelines may therefore need to be revised.