Maternal drug use is a preeminent risk factor for mother-to-child hepatitis C virus transmission: results from a multicenter study of 1372 mother-infant pairs.

This prospective multicenter study evaluated separately the significance of maternal injection drug use (IDU) and human immunodeficiency virus type 1 (HIV-1) coinfection in vertical transmission of hepatitis C virus (HCV). In all, 1372 consecutive, unselected HCV antibody-positive mothers and their infants were studied. Maternal HIV-1 coinfection (crude odds ratios [OR], 1.41; 95% confidence interval [CI], 1.16-1.66; P =.007) and IDU (OR, 1.58; 95% CI, 1.37-1.78; P <.00001) were linked to mother-to-child HCV transmission in unadjusted analysis when all anti-HCV-positive mothers were evaluated. When only HCV RNA-positive mothers were evaluated, maternal IDU, but not maternal HIV-1 coinfection, was significantly associated with mother-to-child HCV transmission. Multivariable analysis confirmed the link between maternal IDU and HCV transmission (adjusted OR [AOR], 1.51; 95% CI, 1.19-1.92; P =.0006), but no association was found with HIV-1 coinfection (AOR, 0.98; 95% CI, 0.73-1.33; P =.93). IDU, but not HIV-1 coinfection, seems to be a preeminent risk factor for vertical HCV transmission.