Longitudinal change of sFlt-1/PlGF ratio in singleton pregnancy with early-onset fetal growth restriction.

Objective To describe, in singleton pregnancies complicated with early-onset fetal growth restriction (FGR), the progressing values of the sFlt-1/PlGF ratio in the weeks prior to delivery, differentiating cases with and without pre-eclampsia (PE). Methods Prospective cohort observational study of early-onset FGR cases followed with maternal serum determinations of the sFlt-1/PlGF ratio from diagnosis to delivery. Measurements were made at weekly intervals and within the last 48 hours before birth. Absolute values, percentage increases between intervals and previously described cut-off values of 38 (suspicion of PE), 85 (aid in diagnosis of PE), and 655 (high risk for imminent delivery), were used for analysis of the sFlt-1/PlGF ratio. Two groups were compared: FGR (n = 37) vs. FGR + PE (n = 36). Results Overall perinatal survival was 63/73 (86.3%). An sFlt-1/PlGF ratio above 38 were observed four weeks before delivery in most FGR and FGR + PE cases (73% and 100%, respectively), but absolute values of the sFlt-1/PlGF ratio were significantly higher in FGR + PE. Extremely elevated values of the ratio (≥655) within the last 48 hours before delivery were found in 65% of cases of FGR + PE, but only in 8% of isolated FGR cases (p < 0.001). Conclusion Most early-onset FGR show elevated sFlt1/PlGF ratio from four weeks before delivery, and values are even higher if there is a concurrent PE. However, repeated measurements of the ratio have limited value, being only useful to anticipate the need for imminent delivery in the FGR + PE group when values ≥655 are reached.