Characterization of the Soluble fms-Like Tyrosine Kinase-1 to Placental Growth Factor Ratio in Pregnancies Complicated by Fetal Growth Restriction

In Brief OBJECTIVE: To characterize the values of the soluble fms-like tyrosine kinase-1 (sFlt-1) to placental growth factor (PlGF) ratio in pregnancies with fetal growth restriction with or without concurrent preeclampsia or hemolysis, elevated liver enzymes and low platelets syndrome (HELLP) and in pregnancies with normally grown fetuses with or without concurrent preeclampsia or HELLP. METHODS: This is a case–control study performed in two centers (Berlin and Madrid) consisting of 171 singleton pregnancies complicated by fetal growth restriction (n=27), preeclampsia or HELLP (n=105) or preeclampsia or HELLP and fetal growth restriction (n=39) pairwise matched by gestational age with 171 healthy control pregnancies. Automated measurement of sFlt-1 and PlGF in maternal serum samples was performed after diagnosis (cases) and in gestational-age matched healthy control samples. Samples were analyzed for two timeframes: before and at or after 34 weeks of gestation. RESULTS: Pregnancies with fetal growth restriction, preeclampsia or HELLP, and preeclampsia or HELLP and fetal growth restriction showed higher median values of sFlt-1/PlGF ratio than control pregnancies both before 34 weeks of gestation (90, 231, 514, and 3, respectively, P<.001) and at or after 34 weeks of gestation (117, 66, 165, and 11, respectively, P<.001). The differences among the case subgroups were not statistically different. CONCLUSION: Fetal growth restriction is characterized by elevated maternal sFlt-1/PlGF ratio, reaching values as high as those observed in preeclampsia or HELLP. LEVEL OF EVIDENCE: II Fetal growth restriction is characterized by elevated maternal soluble fms-like tyrosine kinase-1 to placental growth factor ratio both before and at or after 34 weeks of gestation, reaching values as high as those observed in preeclampsia.