Amniotic Fluid L-Type Fatty Acid-Binding Protein in Predicting Fetal Condition

Abstract

Ultrasonography and fetal heart rate monitoring are subjective assessments of fetal condition, which warrants the need for objective markers to predict fetal condition. Urinary L-type fatty acid-binding protein (L-FABP) levels correlate with hypoperfusion. Elevated amniotic fluid L-FABP levels may represent fetal tissue hypoperfusion since the amniotic fluid contains fetal urine. In this study, we aimed to analyze the effectiveness of amniotic fluid L-FABP as a predictor of fetal condition. We classified singleton pregnancies into groups based on fetal growth restriction (FGR) with and without fetal blood flow abnormalities (FGR and healthy-FGR groups, respectively) and the non-FGR group (control group). We collected amniotic fluid at the time of vaginal delivery, cesarean section and amniocentesis, and compared the patient characteristics, clinical outcomes and amniotic fluid levels of L-FABP between the groups. We analyzed 153 singleton pregnancies and 186 amniotic fluid samples (FGR group, 6 (3.9%) pregnancies and 23 (12.4%) samples; healthy-FGR group, 15 (9.8%) pregnancies and 20 (10.7%) samples; control group, 132 (86.3%) pregnancies and 143 (76.9%) samples). The amniotic fluid L-FABP level was significantly higher in the FGR group compared to that in the healthy-FGR and control groups. Multivariate analysis revealed that the amniotic fluid L-FABP level was not affected by fetal body weight. Additionally, the amniotic fluid L-FABP levels increased significantly in cases with fetal blood flow abnormalities or early gestational age. Therefore, amniotic fluid L-FABP level may be an objective and accurate predictive marker of fetal condition.

Keywords: L-type fatty acid-binding protein; amniotic fluid; fetal blood flow abnormality; fetal condition; fetal growth restriction.