Longitudinal Determination of Serum Placental Protein 13 during Development of Preeclampsia

<i>Objective:</i> To determine maternal serum placental protein 13 (PP13) in normal pregnancy and preeclampsia. <i>Methods:</i> A prospective, longitudinal study with 41 normal pregnant women, 18 cases with preterm delivery or cervix insufficiency and 4 with developing late-onset preeclampsia. Six hundred and sixty-six maternal blood samples were obtained every 2–4 weeks starting at 5–8 weeks gestation (10–12 samples/patient) and tested for serum PP13 by ELISA. <i>Results:</i> In normal pregnant women delivering at term, median maternal serum PP13 levels were growing from 166 to 202 pg/ml and 382 pg/ml in the first, second and third trimester, respectively. Preeclamptic women had significantly reduced PP13 levels in the first trimester (multiples of median of 0.14 at 7–8 weeks; p = 0.005 compared to normal). PP13 in the third trimester was significantly higher compared to normal at 35–36 weeks with PP13 multiples of median of 1.79. <i>Conclusion:</i> This preliminary study indicates that low levels of PP13 in early pregnancy identify at-risk pregnancies, whereas high levels precede the syndrome in late pregnancy and suggest syncytiotrophoblast necrosis.