Background: The sFlt-1/PlGF ratio has proven predictive value in diagnosing preeclampsia. Referring to a study from 18 American perinatal centers, we present results from 2 European centers showing the significant value of those markers in predicting severe perinatal outcomes in hypertensive disorders of pregnancy. Methods: A total of 1630 patients with suspected or confirmed placental insufficiency, hospitalized in two tertiary perinatal centers in Poland and Macedonia, were assessed for their sFlt-1/PlGF ratio. Due to incomplete data, perinatal outcomes were only obtained for 1196 patients. They were sorted into two groups according to the value of the sFlt-1/PlGF ratio (<40 and ≥40). The aim of this study was to predict adverse perinatal outcomes in terms of days to delivery, gestational age, birth weight, and cord blood pH. Results: The strongest negative correlation was observed between the index values and the number of days until delivery (R = −0.48; p < 0.001). In a group of patients with an index value of ≥40, the AUC was 0.9955 (95% CI: 0.9913 to 0.9996), with a sensitivity of 52%, a specificity of 78%, a positive predictive value of 77%, and a negative predictive value of 53%. For patients who were tested before 37 weeks of gestation, 66% of women with a ratio of ≥40 delivered within 7 days of the test, and 80% of those with a ratio of <40 delivered more than 7 days after the test, with a sensitivity of 68%, a specificity of 79%, a positive predictive value of 66%, and a negative predictive value of 80%. Conclusions: In women with hypertensive disorders, the sFlt-1/PlGF ratio can be used to predict the time to delivery. A cut-off of 40 is very useful in predicting severe perinatal outcomes.