Antiphospholipid syndrome (APS) is classified as the association of thrombotic events and/or obstetric morbidity in patients persistently positive for antiphospholipid antibodies (aPL). APS is also the most frequently acquired risk factor for a treatable cause of recurrent pregnancy loss and increases the risk of conditions associated with ischemic placental dysfunction, such as stillbirth, intrauterine death, preeclampsia, premature birth, and fetal growth restriction. The use of low-dose aspirin and heparin has improved the pregnancy outcome in obstetric APS and approximately 70% of pregnant women with APS will deliver a viable live infant. However, current management does not prevent all maternal, fetal, and neonatal complications of APS and the current treatment fails in 20 to 30% of APS pregnancies, raising the need to explore other treatments to improve obstetrical outcome. Two clinical studies of retrospective design have suggested that the immunomodulator hydroxychloroquine (HCQ) may play a role in the prevention of pregnancy complications in women with aPL and APS. The randomized controlled multicenter trial of hydroxychloroquine versus placebo during pregnancy in women with antiphospholipid antibodies (HYPATIA) of HCQ versus placebo will provide scientific evidence on the use of HCQ in pregnant women with aPL.