Analysis of circulating annexin A5 parameters during pregnancy: Absence of differences between women with recurrent spontaneous pregnancy losses and controls

Objective: We investigated whether levels of annexin A5 (AnxA5), AnxA5 anticoagulant activity and binding, and anti-AnxA5 antibodies might be altered in women with previous histories of recurrent spontaneous pregnancy losses (RSPL) when tested during pregnancy. Study design: Ninety pregnant women with histories of 3 or more RSPL (cases) and 150 women without adverse pregnancy histories (controls) were assayed for these AnxA5 parameters. Results: There were no significant differences between cases and controls in AnxA5 levels (median, 23.1 ng/mL [range, 2.1-201.1 ng/mL] vs 19.7 ng/mL [2.1-151.5 ng/mL]; P = .20), AnxA5 anticoagulant activity (183% [101%-236%] vs 168% [128%-256%]; P = .39) and binding (6.0 ng/aliquot PL [2.1-19.5 ng/aliquot PL) vs 6.1 ng/aliquot PL [1.6-16.8 ng/aliquot PL]; P = .72), and anti-AnxA5 antibody levels. Conclusions: AnxA5 parameters do not distinguish between cases and controls when tested during pregnancy. The pregnant state itself appears to be associated with altered levels of AnxA5 parameters.