Unexplained fetal death is associated with increased concentrations of anti-angiogenic factors in amniotic fluid.

Angiogenesis is critical for successful pregnancy. An anti-angiogenic state has been implicated in preeclampsia, fetal growth restriction and fetal death. Increased maternal plasma concentrations of the anti-angiogenic factor, soluble vascular endothelial growth factor receptor (sVEGFR)-1, have been reported in women with preeclampsia and in those with fetal death. Recent observations indicate that an excess of sVEGFR-1 and soluble endoglin (sEng) is also present in the amniotic fluid of patients with preeclampsia. The aim of this study was to determine whether fetal death is associated with changes in amniotic fluid concentrations of sVEGFR-1 and sEng, two powerful anti-angiogenic factors. Study design. This cross-sectional study included patients with fetal death (n = 35) and controls (n = 129). Fetal death was subdivided according to clinical circumstances into: (1) unexplained (n = 25); (2) preeclampsia and/or placental abruption (n = 5); and (3) chromosomal/congenital anomalies (n = 5). The control group consisted of patients with preterm labor (PTL) who delivered at term (n = 92) and women at term not in labor (n = 37). AF concentrations of sVEGFR-1 and sEng were determined by ELISA. Non-parametric statistics and logistic regression analysis were applied. Results. (1) Patients with a fetal death had higher median amniotic fluid concentrations of sVEGFR-1 and sEng than women in the control group (p < 0.001 for each); (2) these results remained significant among different subgroups of stillbirth (p < 0.05 for each); and (3) amniotic fluid concentrations of sVEGFR-1 and those of sEng above the third quartile were associated with a significant risk of unexplained preterm fetal death (adjusted OR = 10.8; 95%CI 1.3-89.2 and adjusted OR 87; 95% CI 2.3-3323, respectively). Conclusion. Patients with an unexplained fetal death at diagnosis are characterized by an increase in the amniotic fluid concentrations of sVEGFR-1 and sEng. These observations indicate that an excess of anti-angiogenic factors in the amniotic cavity is associated with unexplained fetal death especially in preterm gestations.