ProblemWomen with antiphospholipid syndrome (APS) are at risk for pregnancy complications. Antiphospholipid antibodies (aPL) alter trophoblast function by triggering an inflammatory cytokine response; modulating angiogenic factor secretion; and inhibiting migration. While patients with APS are often treated with hydroxychloroquine (HCQ), its effect on trophoblast function is poorly understood.Method of study A human first trimester trophoblast cell line was treated with or without antihuman b 2 GPI mAbs in the presence or absence of HCQ. Supernatants were analyzed by ELISA. Cell migration was measured using a colormetric assay. ResultsAntiphospholipid antibodies-induced trophoblast IL-8, IL-1 b, PlGF, and sEndoglin secretion were not altered by HCQ. aPL-induced inhibition of trophoblast migration was partially reversed by HCQ, even though HCQ significantly increased secretion of pro-migratory IL-6 to greater than baseline. aPL-induced upregulation of TIMP2 appears to inhibit trophoblast migration; the inability of HCQ to prevent aPL-induced TIMP2 may explain why migration was only partially restored.