Objective The Fas-Fas ligand (FasL) pathway of apoptosis contributes to immune tolerance at the feto-maternal interface and has been ascribed a role in implantation and placental development. We aimed to investigate concentrations of soluble Fas (sFas) and soluble FasL (sFasL) in maternal, fetal and neonatal serum from intrauterine-growth-restricted (IUGR, associated with impaired maternal-fetal tolerance, increased trophoblast apoptosis and uteroplacental vascular insufficiency) and appropriate-for-gestational-age-(AGA) pregnancies.

Methods Circulating sFas and sFasL concentrations were measured in 40 mothers and their 20 IUGR and 20 AGA singleton full-term fetuses-neonates on postnatal day 1-(N1) and 4-(N4).

Results No significant differences in sFas and sFasL concentrations were observed between groups. However, maternal sFas concentrations were marginally elevated in the IUGR group (p = 0.054). In both groups, maternal sFas concentrations were increased compared to fetal, N1 and N4 ones (p⩽0.005 in AGA and p<0.001 in IUGR, in all cases). Maternal sFasL concentrations were lower compared to fetal, N1 and N4 ones (p<0.001 in all cases). Fetal sFasL concentrations were increased compared to maternal, but lower compared to N4 ones (p<0.001 in AGA and p⩽0.020 in IUGR in all cases). N4 sFasL concentrations were elevated compared to N1 ones (p<0.001 in all cases).

Conclusions The elevated maternal sFas concentrations in the IUGR cohort may reflect maternal immune intolerance, leading to increased trophoblast apoptosis and abnormal placentation. Furthermore, the results of this study imply an acceleration of Fas-FasL-mediated apoptosis during delivery and a respective decrease postpartum in both normal and IUGR pregnancies.