Antiphospholipid syndrome in patients with fetal death: a prospective longitudinal cohort study.

To investigate the causes of fetal death, focusing on maternal antiphospholipid syndrome diagnosis, and to follow the patients for changes in antiphospholipid antibodies, subsequent pregnancy outcomes, and thrombotic events. This is a prospective longitudinal cohort study that recruited patients who were hospitalized for fetal death at ≥ 10 weeks of gestation from three tertiary hospitals in China. Antiphospholipid syndrome was diagnosed according to the 2006 Sydney classification criteria. In total, 159 patients were recruited to the study; 3 were excluded and 144 of whom tested for aPLs. Among these, 126 (87.5%) were available for diagnostic analysis of antiphospholipid syndrome, 13 (10.3%) of which carried a diagnosis of antiphospholipid syndrome. Meanwhile, 136 of 156 patients had fetal samples for which copy number variation sequencing was completed, and 12 (8.8%) of which carried a diagnosis of fetal chromosomal abnormalities. During later follow-up, among the 13 patients with antiphospholipid syndrome, seven were persistently positive serostatus of antiphospholipid antibodies, four exhibited fluctuation, and one had negative conversion; four patients with subsequent pregnancies received guideline-based therapy and had term livebirths. None of the participants experienced thrombotic events. Maternal antiphospholipid syndrome was found to be one of the important causes of fetal death, contributing 10.3% of cases of fetal death at ≥ 10 weeks of gestation, slight ahead of fetal chromosomal abnormalities. Follow-up indicated that the serostatus of antiphospholipid antibodies may fluctuate significantly in some patients with antiphospholipid syndrome.Clinical trial registration:As this study was an observational study, we did not register it as a clinical trial.