Low-titer antiphospholipid antibodies is associated with increased risk of late preterm stillbirth

Abstract

Antiphospholipid (aPL) antibodies are present in up to 42% of patients with pregnancy loss. Patients with low-titer aPL antibodies who do not meet Sapporo criteria for antiphospholipid syndrome (APLS) often receive conflicting counseling in regards to pregnancy loss and perinatal outcomes by both hematologists and perinatologists. We performed a retrospective cohort study of pregnant patients who had aPL testing and compared pregnancy outcomes between subjects with low-titer aPL and those with negative aPL. Low-titer aPL was defined as positive anticardiolipin or anti-B2 glycoprotein IgG or IgM < 40 GPL or MPL or < 99th percentile. The primary outcome consisted of early pregnancy loss (< 13 weeks), spontaneous abortion (≥13, < 20 weeks), and fetal demise/stillbirth (≥20 weeks). Bivariable and multivariable analyses were performed. There were 2,898 patients with a pregnancy episode and aPL testing. Compared to those with negative aPL, low-titer aPL individuals were more likely to be younger, identify as Black or African-American, have hematologic or autoimmune disorders, have a history of substance use disorder or psychiatric disorder. Notably, there was increased use of aspirin but no difference in anticoagulation use in this group. (Table 1). After multivariable analysis, patients with low-titer aPL were not at higher risk for early pregnancy loss or spontaneous abortion when compared to those with negative aPL. However, they were at higher risk for stillbirth between 28-37 weeks compared with their negative aPL counterparts with an OR 1.81 (1.01-3.23), once adjusted for high risk comorbidities. (Table 2). Patients with low-titer aPL had higher rates of expected autoimmune and hematologic disorders compared to those with negative aPL. While there was no increased risk of spontaneous abortion, these patients were more likely to have a late preterm fetal demise, even when adjusted for medical and social comorbidities and aspirin use. While these patients do not carry a formal APLS diagnosis, they have a higher risk of stillbirth than patients with negative aPL.View Large Image Figure ViewerDownload Hi-res image Download (PPT)