INTRODUCTION: Hydroxychloroquine (HCQ), originally an antimalarial drug, is currently used to treat multiple disorders, especially rheumatic diseases. Given its good efficacy and safety, HCQ is widely administered in pregnant patients. However, the safety profile of HCQ during pregnancy remains controversial due to limited research. In addition, HCQ has been reported to reduce preeclampsia in patients with systemic lupus erythematosus (SLE) and could potentially alleviate the symptom of preeclampsia. However, the clinical profile and molecular mechanism of HCQ in preeclampsia is yet to be fully understood. METHOD: We reviewed the literature on HCQ treatment in pregnancy with rheumatic diseases and preeclamp-sia in PubMed and Web of Science. We also discussed the safety of long-term therapy with HCQ during pregnancy. RESULTS: HCQ mainly modulates autoimmune response through inhibition of lysosomal function, toll-like receptor (TLR) signalling, nicotinamide adenine dinucleotide phosphate-mediated oxidative stress and autophagy. Benefits of HCQ in treating rheumatic diseases, including antiphospholipid syndrome, rheumatoid arthritis and Sjogren's syndrome during pregnancy, has been demonstrated in clinics. In particular, multiple clinical guidelines recommend HCQ as an indispensable therapeutic drug for pregnant patients with SLE. Additionally, it may potentially function in preeclampsia to improve clinical symptoms. CONCLUSION: HCQ is effectively used for rheumatic diseases during pregnancy. The benefits of HCQ treatment in rheumatic diseases outweigh the risk of adverse reactions it induces in pregnant women.