Evaluating the effectiveness of quadruple therapy for chronic histiocytic intervillositis

Objective To evaluate the effectiveness of quadruple therapy (Aspirin, low molecular weight heparin, hydroxychloroquine and prednisone) on mitigation of chronic histiocytic intervillositis (CHI) in subsequent pregnancies. Methods This is a case series using chart review of patients referred to Obstetric Medicine and Maternal Fetal Medicine clinics in our institution from January 2021 to April 2025 with a history of CHI. Data collected include demographics, pregnancy histories, delivery information, birthweights, relevant medical history, medications, the investigational quadruple therapies, and placental pathologies. Descriptive analyses were performed. Ethics board at the University of Alberta approved the study. Results Twenty patients were referred for preconception counseling and/or pregnancy management given a history of CHI. Nine patients subsequently had 13 pregnancies while on the quadruple therapy protocol. Average age of the patients on treatment was 33 years old. Livebirth rate was 100% in the subsequent treated pregnancies (excluding first trimester losses). In the first subsequent treated pregnancy, the median gestational age at delivery was 37 0 weeks (compared to 33 6 weeks for the index pregnancy) and the median birthweight was 2710 g. A similar trend was observed in the second treated pregnancy compared to the index. More than two-thirds of the placentas from the treated pregnancies showed a reduction in the extent of inflammation from CHI compared to the respective index pregnancies. Conclusion Patients with a history of CHI who were treated with the quadruple therapy in subsequent pregnancies had good livebirth rate, longer latency of gestation, and less inflammation on placental pathologies in the treated pregnancies.