Extreme sFlt-1/PlGF ratio in preeclampsia and fetal growth restriction: is there prognostic value beyond gestational age and fetal biometry?

This study evaluated whether, in pregnancies with extreme angiogenic imbalance, defined by a soluble fms-like tyrosine kinase-1 to placental growth factor ratio greater than 600, the absolute ratio provides additional prognostic value for perinatal death or severe morbidity beyond gestational age and estimated fetal weight. A secondary objective was to assess the contribution of ratio kinetics and placental growth factor levels in fetal growth restriction. We conducted a retrospective observational cohort study including 132 singleton pregnancies managed at a tertiary referral hospital between June 2015 and September 2024. Outcomes were intrauterine fetal death, death within the first week, death within the first year, severe morbidity with major sequelae, and a composite adverse outcome. Baseline models including gestational age and estimated fetal weight at the time of ratio greater than 600 were compared with models additionally including the logarithm of the ratio. Event rates were 8.3%, 15.9% week, 20.6%, 29.5%, and 43.9%, respectively. Adding the ratio did not improve discrimination for any endpoint. A ratio greater than 600 was, however, associated with shorter time to delivery. In the serial subset, the rate of increase of the ratio improved prediction of death within the first week. In fetuses with growth restriction, lower placental growth factor levels were associated with severe morbidity. In this extreme range, the ratio mainly reflects disease imminence rather than outcome severity. Ratio kinetics may identify acute deterioration, whereas placental growth factor may better reflect residual placental reserve and fetal viability, especially in growth-restricted fetuses.