Longitudinal determination of serum placental protein 13 during development of preeclampsia

Objective: To determine maternal serum placental protein 13 (PP13) in normal pregnancy and preeclampsia. Methods: 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. Results: 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. Conclusion: 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.