Hydroxychloroquine in obstetrics: potential implications of the prophylactic use of hydroxychloroquine for placental insufficiency during pregnancy

Proper placentation during early pregnancy is a key factor for maintaining a healthy pregnancy. Placental insufficiency leads to critical complications such as preeclampsia, fetal growth restriction, and fetal demise. These complications are often associated with pathological findings of restricted remodeling and obstructive lesions of the myometrial spiral arteries, which have high recurrence rates during subsequent pregnancies. Currently, there are no pharmacological interventions other than aspirin for the prevention of preeclampsia. Hydroxychloroquine (HCQ), a well-known antimalarial drug, reduces inflammatory and thrombotic changes in vessels. For decades, the use of HCQ for autoimmune diseases has resulted in the successful prevention of both arterial and venous thrombotic events and has been extended to the treatment of lupus and antiphospholipid antibody syndrome during pregnancy. HCQ reduces the risk of preeclampsia with lupus by up to 90%. Several recent studies have investigated whether HCQ improves pregnancy outcomes in women with a history of poor outcomes. In addition, in vitro and animal studies have demonstrated the beneficial effects of HCQ in improving endothelial dysfunction and alleviating hypertension and proteinuria. Therefore, we hypothesized that HCQ has the potential to attenuate the vascular inflammatory and thrombogenic pathways associated with placental insufficiency and conducted a multicenter clinical trial on the efficacy of combining aspirin with HCQ for pregnancies at high risk for preeclampsia in Korea. This study summarizes the potential effects of HCQ on pregnancies with placental insufficiency and the implications of HCQ treatment in the field of obstetrics.