An intermediate sFlt-1/PlGF ratio indicates an increased risk for adverse pregnancy outcome

The sFlt-1/PlGF ratio is a valid marker in diagnosing or excluding preeclampsia. The currently used cut offs frame an intermediate zone of 33-85 (<34⁰ weeks) or 33-110 (≥34⁰ weeks), respectively. In this study we sought to evaluate the relevance of an intermediate sFlt-1/PlGF ratio for the clinical pregnancy course and outcome.

We retrospectively analysed 533 consecutive patients with sFlt-1/PlGF ratio measurements for suspected preeclampsia. In patients with an intermediate sFlt-1/PlGF ratio, fetal and maternal characteristics and also pregnancy outcome were documented. Furthermore, we compared the patient groups with <34⁰/34⁰-36⁶/≥37⁰ gestational weeks at first visit.

83/533 (15.6%) patients had an intermediate sFlt-1/PlGF ratio. Maternal or fetal diseases or twin pregnancies occurred in 87.9%. Preeclampsia/HELLP syndrome developed in 31.3% but were mostly mild or moderate (65.4%). However, severe adverse outcome was observed in 36.1% with severe preeclampsia in 10.8%. Even if further pregnancy duration and gestational week correlated negatively (r=-0.424; p<0.001), 92% of patients, tested with <34⁰ weeks delivered prematurely. The overall preterm birth rate was 27.7%.

Patients with an intermediate sFlt-1/PlGF ratio are at risk for severe adverse outcome. An intermediate sFlt-1/PlGF ratio indicates a risk for preterm birth, independent from the occurrence of preeclampsia.