The incidence of hepatitis C virus (HCV) infection in reproductive-aged adults quadrupled during the past decade. Hepatitis C can progress to advanced liver disease and be transmitted perinatally. Highly effective curative hepatitis C treatment is available but is not recommended in pregnancy. Using the Surveillance for Emerging Threats to Mothers and Babies Network, we describe timing of positive RNA testing among pregnant people with HCV (HCV RNA detected during or within one year prior to pregnancy). Four US jurisdictions reported 1161 pregnancies during 2018–2021 among people with hepatitis C: 75.9% were multiparous; and 21.4% had their first peri-pregnancy HCV RNA detected prior to pregnancy, indicating potential missed treatment opportunities to improve maternal health and prevent perinatal transmission.