Change in prevalence of clinical events with increasing LAC positivity. The frequency of TEs, stillbirth (SB), and live birth (LB) varied with increasing number of positive results on LAC assays: patients with 0 of 4 assays positive (ie, LAC negative) had the lowest prevalence of TEs and SB but the highest prevalence of recurrent pregnancy loss. In contrast, patients with 4 of 4 positive results on LAC assays had the highest prevalence of TEs and SB. Patients with either 1 of 4 or 2 of 4 positive LAC assay results appeared to have the same event frequencies.