Better prediction for FGR (fetal growth restriction) with the sFlt-1/PIGF ratio: A case-control study

The aim of this study was to check whether the sFlt-1/PIGF ratio, established as the biomarker for preeclampsia, reduces the false positive rate of late fetal growth restriction (FGR) detection by ultrasound biometry. This was a prospective case-control study, conducted at one regional maternity hospital in Romania. Study participants included singleton pregnancy women for whom the estimated fetal weight (EFW) at 28 to 35 weeks was < 10 percentiles and as controls, pregnant women with EFW >10 percentiles. All pregnancies were dated in the first trimester by crown-rump-length. We also recorded maternal characteristics, pregnancy and neonatal outcomes. The primary outcome measures were the relation between the sFlt-1/PIGF ratio and incidence of FGR. Secondary outcome was establishing a threshold for statistical significance of the marker and influence of other conditions (e.g., pre-eclampsia) on the accuracy of the marker in FGR prediction. Included in the study were 37 pregnant women and 37 controls. When we used ultrasound (US) biometry and maternal risk factors to estimate EFW <10 percentiles, the sensitivity was 44.4% with a specificity of 89% for an FPR (false positive result) of 10%. When we combined the US biometry and maternal risk factors with sFlt1/PIGF ratio, for a cut off of 38, the sensitivity was 84.21%, and the specificity was 84.31% for an FPR of 10%. The cut off value (36) did not change if we considered all cases of SGA, including those with associated preeclampsia or if we considered only FGR cases without associated preeclampsia. When associated with maternal factors and US biometry, the sFlt1/PIGF ratio enhanced the sensitivity for detecting late FGR.