Annexin A5 levels in midtrimester amniotic fluid: Association with intrauterine growth restriction

Objective: The purpose of this study was to determine whether amniotic fluid levels of annexin A5 (AF-AnxA5) may be associated with intrauterine growth restriction (IUGR). Study design: Amniotic fluid was obtained in a cohort of pregnant patients (n = 172) undergoing amniocentesis at 15 to 24 weeks' gestation and annexin A5 (AnxA5) levels were determined with enzyme-linked immunosorbent assay (ELISA). Patients who developed IUGR were compared with the remainder of the cohort. Results: AF-AnxA5 levels significantly increased through gestation (P = .003). The mean level of AF-AnxA5 in IUGR patients (n = 15) was significantly higher (P = .028) than in the remainder of the cohort (n = 130). Elevated AF-AnxA5 > 20 ng/mL was associated with a relative risk of 3.5 for the development of IUGR (P = .023). Conclusion: AnxA5 is present in amniotic fluid and increases through gestation from 15 to 24 weeks. Elevated AF-AnxA5 levels were present in patients who developed IUGR. AF-AnxA5 may be a useful marker for identifying pregnancy abnormalities.