Influence of hepatitis C viral parameters on pregnancy complications and risk of mother-to-child transmission

Background & Aims: With the World Health Organization plan for hepatitis C elimination by the year 2030, and recent guideline recommendations to screen all women during pregnancy for HCV, data on HCV in pregnancy are needed to determine the association of HCV viremia with adverse pregnancy outcomes and mother-to-child transmission (MTCT). Methods: This retrospective cohort study was performed in Ontario, Canada, using population-based administrative healthcare data. Individuals were stratified based on whether they had active HCV viremia during pregnancy or resolved viremia at time of pregnancy. Peak HCV viral load was determined. Logistic regression was used to determine the association of viremia with adverse pregnancy outcomes; maternal HCV RNA levels were evaluated as a predictor of MTCT. Results: We identified a total of 2,170 pregnancies in 1,636 women who were HCV RNA positive prior to pregnancy; 1,780 (82%) pregnancies occurred in women who were HCV RNA positive during pregnancy. Patients who were HCV RNA positive during pregnancy were more likely to have preterm delivery (18% vs. 12%, p = 0.002), intrahepatic cholestasis of pregnancy (4% vs. <2%, p = 0.003), and post-partum hemorrhage (9% vs. 5%, p = 0.013), and less likely to have gestational diabetes (6% vs. 10%, p = 0.008) than those with resolved infection. Only 511 (29%) infants had screening consistent with guidelines after birth; there was an estimated 3.5% risk of MTCT. HCV RNA ≥6.0 log₁₀ IU/ml was significantly associated with MTCT (exact odds ratio 3.4, p = 0.04). Conclusion: Active HCV viremia among individuals with a history of HCV infection significantly increases adverse pregnancy outcomes. Few infants are screened for MTCT. Higher HCV RNA is associated with increased risk of MTCT. Lay summary: The prevalence of hepatitis C has increased in women of child-bearing age and has important implications for women who become pregnant and their infants. We evaluated the effect that hepatitis C has on pregnancy outcomes as well as the rate of hepatitis C transmission to infants in a large database with linked mother-infant records. We found that active hepatitis C during pregnancy increased the risk of pregnancy complications. We also identified very low rates of testing of infants born to mothers with hepatitis C, but found higher rates of hepatitis C transmission to infants in mothers with higher virus levels.