ObjectiveTo determine the minimum blood pressure increases that would confirm or exclude, with the greatest predictive values, hypertensive disorders of pregnancy (HDP) in pregnant adolescents after 24 weeks gestation.MethodsWe conducted a case-control study of pregnant women aged ≤19 years with and without HDP. Using systolic and diastolic blood pressure increases, a predictive analysis was performed, and the area under the curve was calculated.ResultsThe cases and controls had systolic blood pressure increases of 45.3 ± 17.5 mm Hg and 6.4 ± 7.9 mm Hg, respectively (P = 0.001) and diastolic blood pressure increases of 30.8 ± 11.7 mm Hg and 3.5 ± 5.7 mm Hg, respectively (P = 0.001). Systolic and diastolic increases of ≥20 mm Hg showed the greatest sensitivity and specificity. A combined analysis showed that an increase of ≥20 mm Hg had a greater positive likelihood ratio of 35.4 (95% CI 22.4–55.9) and negative likelihood ratio of 0.10 (95% CI 0.07–0.13), with an area under the curve of 0.98 (95% CI 0.96–0.99).ConclusionsSystolic and diastolic blood pressure increases of ≥20 mm Hg must be considered in the diagnostic criteria for preeclampsia and gestational hypertension among pregnant adolescents past 24 weeks gestation.