Maternal and Perinatal Outcomes Associated With Extremely High Values for the sFlt‐1 (Soluble fms‐Like Tyrosine Kinase 1)/PlGF (Placental Growth Factor) Ratio

Abstract

Background

There is little knowledge about the significance of extremely high values (>655) for the ratio of sFlt-1 (soluble fms-like tyrosine kinase 1) to PlGF (placental growth factor). This study aims to describe the time-to-delivery interval and maternal and perinatal outcomes when such values are observed during the assessment of suspected or confirmed placental dysfunction based on clinical or sonographic criteria.

Methods and Results

A multicenter retrospective cohort study was conducted on 237 singleton pregnancies between 20+0 and 37+0 weeks of gestation, included at the time of first demonstrating an sFlt-1/PlGF ratio >655. Although clinicians were aware of this result, standard protocols for delivery indications were followed. Outcomes were compared for women with and without preeclampsia at inclusion.

In the preeclampsia group (n=185, of whom 77.3% had fetal growth restriction), severe preeclampsia features and fetal growth restriction in stages III or IV were present in 49.2% and 13.5% of cases, respectively, at inclusion, and in 77.3% and 28.6% of cases, respectively, at delivery. In the group without preeclampsia (n=52, of whom 82.7% had fetal growth restriction), these figures were 0% and 30.8% at inclusion and 21.2% and 50% at delivery, respectively. Interestingly, 28% of women without initial preeclampsia later developed the condition.

The median time to delivery was 4 days (interquartile range: 1–6 days) for women with preeclampsia and 7 days (interquartile range: 3–12 days) for those without preeclampsia (π<0.01). Overall, perinatal mortality was 62.1% before 24 weeks; severe morbidity exceeded 50% before 29 weeks but was absent from 34 weeks onward. Maternal serious morbidity remained high across all gestational ages.

Conclusions

An sFlt-1/PlGF ratio >655 is almost invariably associated with preeclampsia or fetal growth restriction that progresses rapidly. In tertiary care settings, maternal adverse outcomes were consistently high across gestation, whereas perinatal adverse outcomes decreased as pregnancy advanced.