Criteria and non-criteria antiphospholipid autoantibodies screening in patients with late pregnancy morbidity: A cross-sectional study

Introduction: Antiphospholipid syndrome (APS) is a cause of pregnancy morbidity. We aim to determine the frequency of criteria and non-criteria anti-phospholipid (aPL) autoantibodies in patients admitted for unexplained fetal death (UFD), pre-eclampsia (PE) and/or fetal growth restriction (FGR). Methods: All consecutive patients with UFD, PE and/or FGR followed in the department of Obstetrics, Bichat Hospital, University of Paris, Paris, between January 2019 and December 2021 were screened. Patients with available serum stored from the index pregnancy were included. Patients with previously known APS or twin pregnancy were excluded. Testing for aPL autoantibodies included anti-cardiolipin (aCL), anti-beta 2GPI (a beta 2GPI), anti-phosphatidylethanolamine (aPE), anti-phosphatidylserine/prothrombin (aPS/PT) IgG/IgM and anti-annexin V IgG. When available, placenta specimens were analyzed by a pathologist blinded to the aPL status. All clinical characteristics, pregnancy features, and comorbidities were extracted from electronic medical records. Results: Overall 167 (32 (28.8-35.7) years) patients with UFD (n = 28; 16.8 %), PE (n = 60; 35.9 %) and/or FGR (n = 105; 62.9 %) were screened for aPL autoantibodies. Moderate titers of aPL autoantibodies were detected in 33 (n = 33/167, 19.8 %) patients. aPL autoantibodies were non-criteria aPE IgG/IgM in most cases (n = 28/33, 84.8 %). aPS/PT IgG/IgM were found in 11 (n = 11/33, 33.3 %) cases and aCL or a beta 2GP1 IgG/IgM in 4 (n = 4/33, 12.1 %). Multivariable logistic regression showed that aPL autoantibodies were mostly associated with UFD (OR 4.37 [1.72-11.20], p = 0.002), PE <= 34th week of gestation (3.22 [0.86-11.90], p = 0.070) and chronic deciduitis (8.03 [0.89-67.2], p = 0.060) Discussion: The frequency of aPL autoantibodies, mostly aPE, is high in patients with late pregnancy morbidity and may qualify obstetrical APS.