Purpose: The ratio of soluble fms-like tyrosine kinase 1 (sFlt-1) to placental growth factor (PlGF) is considered a predictive marker of preeclampsia. However, the relationship between the sFlt-1/PlGF ratio and perinatal and neonatal outcomes remains unknown. This study aimed to determine the associations of the sFlt-1/PlGF ratio with perinatal and neonatal outcomes in newborns born to mothers with preeclampsia.Methods: This retrospective cohort study reviewed singleton neonates born to mothers with preeclampsia who underwent testing for the sFlt-1/PlGF ratio. We investigated the relationship between maternal sFlt-1/PlGF ratios and gestational age (GA), birth weight (Bwt), Bwt z-score, morbidities, and mortality of neonates born to mothers tested for the sFlt-1/PlGF ratio. Maternal sFlt-1/PlGF ratios examined within 30 days before delivery were used for analysis. Neonatal morbidities and mortality were investigated only in preterm infants born earlier than 32 weeks GA.Results: A total of 225 neonates were included, of which 163 (72.4%) were preterm infants. GA (<i>R</i>=– 0.577, <i>p</i><0.001), Bwt (<i>R</i>=–0.713, <i>p</i><0.001), and Bwt z-score (<i>R</i>=–0.608, <i>p</i><0.001) exhibited significant negative correlations with the sFlt-1/PlGF ratios. Among the 50 preterm infants born earlier than 32 weeks GA, neonatal morbidities were not significantly associated with the sFlt-1/PlGF ratio after adjusting for GA and Bwt.Conclusion: In mothers with preeclampsia, a higher sFlt-1/PlGF ratio was associated with the delivery of newborns with lower GA and lower Bwt. However, this ratio was not associated with increased morbidity or mortality in premature infants born earlier than 32 weeks GA.