doi:10.1159/000514378engDe La Calle, M.Delgado, J.L.Verlohren, S.Escudero, A.I.Bartha, J.L.Campillos, J.M.Aguarón De La Cruz, A.Chantraine, F.García Hernández, J.Á.Herraiz, I.Llurba, E.Kurka, H.Guo, G.Sillman, J.Hund, M.Perales Marín, A.Gestational Age-Specific Reference Ranges for the sFlt-1/PlGF Immunoassay Ratio in Twin PregnanciesART-2021-124285Objective: Establish reference ranges for the Elecsys® soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PlGF) immunoassay ratio in twin pregnancies. Methods: Data analyzed were from 3 prospective studies: Prediction of Short-Term Outcome in Pregnant Women with Suspected Preeclampsia (PE) (PROGNOSIS), Study of Early-onset PE in Spain (STEPS), and a multicenter case-control study. Median, 5th, and 95th percentiles for sFlt-1, PlGF, and the sFlt-1/PlGF ratios were determined for normal twin pregnancies for 7 gestational windows and compared with the previous data for singleton pregnancies. Results: The reference range analysis included 269 women with normal twin pregnancies. Before 29 weeks'' gestation, median, 5th, and 95th percentiles for sFlt-1/PlGF ratios did not differ between twin and singleton pregnancies. From 29 weeks'' gestation to delivery, median, 5th, and 95th percentiles for sFlt-1/PlGF ratios were substantially higher in twin versus singleton pregnancies. sFlt-1 values were higher in women with twin pregnancies across all gestational windows. PlGF values were similar or higher in twin versus singleton pregnancies; PlGF concentrations increased from 10 weeks + 0 days to 28 weeks + 6 days'' gestation. Conclusions: Reference ranges for the sFlt-1/PlGF ratio are similar in women with twin and singleton pregnancies until 29 weeks'' gestation but appear higher in twin pregnancies thereafter.2021http://zaguan.unizar.es/record/15130810.1159/000514378http://zaguan.unizar.es/record/151308oai:zaguan.unizar.es:151308Fetal Diagnosis and Therapy 48, 4 (2021), 288–296by-nchttps://creativecommons.org/licenses/by-nc/4.0/deed.esinfo:eu-repo/semantics/openAccess