Obstetric antiphospholipid syndrome: A recent classification for an old defined disorder

Obstetric antiphospholipid syndrome (APS) is nowbeing recognized as a distinct entity fromvascular APS. Pregnancymorbidity includes N3 consecutive and spontaneous early miscarriages before 10 weeks of gestation; atleast one unexplained fetal death after the 10thweek of gestation of a morphologically normal fetus; a prematurebirth before the 34thweek of gestation of a normal neonate due to eclampsia or severe pre-eclampsia or placentalinsufficiency. It is not well understood how antiphospholipid antibodies (aPLs), beyond their diagnostic andprognostic role, contribute to pregnancy manifestations. Indeed aPL-mediated thrombotic events cannot explainthe obstetric manifestations and additional pathogenic mechanisms, such as a placental aPL mediated complementactivation and a direct effect of aPLs on placental development, have been reported. Still debated is the possibleassociation between aPLs and infertility and the effect of maternal autoantibodies on non-vascularmanifestations in the babies. Combination of low dose aspirin and unfractionated or low molecular weight heparinis the effective treatment in most of the cases. However, pregnancy complications, in spite of this therapy,can occur in up to 20% of the patients. Novel alternative therapies able to abrogate the aPL pathogenic action eitherby interfering with aPL binding at the placental level or by inhibiting the aPL-mediated detrimental effect areunder active investigation.