Table 8: Validity factors in parallel tests of preeclampsia markers based on the first and second trimesters.

Time sessionPositive result Sensitivity
(95% CI)
Specificity %
(95% CI)
Positive predictive value %
(95% CI)
Negative predictive value %
(95% CI)

First trimesterBoth positive51.0
(40.8–61.1)
96.0
(90.1–98.9)
92.7
(82.4–98.0)
66.2
(57.8–73.8)
First trimesterAt least one positive86.0
(77.6–92.1)
64.0
(53.8–73.4)
70.5
(61.6–78.4)
82.1
(71.1–89.8)
Second trimesterBoth positive56.0
(45.7–65.9)
97.0
(91.5–99.4)
94.9
(85.9–98.9)
68.8
(60.5–76.3)
Second trimesterAt least one positive94.0
(87.4–97.8)
54.0
(43.7–74.8)
67.1
(58.7–74.8)
90.0
(79.5–96.2)