Maternal Serum Placental Growth Factor, Pregnancy-Associated Plasma Protein-A and Free β-Human Chorionic Gonadotrophin at 30-33 Weeks in the Prediction of Pre-Eclampsia

Abstract

Objective: To investigate the potential value of maternal serum concentrations of free β-human chorionic gonadotrophin (β-hCG), pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PlGF) at 30-33 weeks of gestation in the prediction of pre-eclampsia (PE) developing at or after 34 weeks. Methods: Serum free β-hCG, PAPP-A and PlGF were measured at 11-13 and at 30-33 weeks of gestation in a case-control study of 50 cases that developed PE at or after 34 weeks and 250 unaffected controls. The measured concentration of metabolites was converted into multiples of the unaffected median (MoM) and the MoM values in the PE and control groups were compared. Results: At 11-13 weeks, serum PlGF and PAPP-A, but not free β-hCG, were significantly lower in the PE group than in the controls (0.824, 0.748 and 0.857 vs. 1.000 MoM). At 30-33 weeks in the PE group, PlGF was reduced (0.356 MoM), free β-hCG was increased (1.750 MoM), but PAPP-A was not significantly different (0.991 MoM) from control (1.000 MoM). In screening for PE at 30-33 weeks by a combination of maternal characteristics and serum PlGF, the estimated detection rates, at a false-positive rate of 10%, of intermediate PE (requiring delivery at 34-37 weeks) and late PE (with delivery after 37 weeks) were 85.7 and 52.8%, respectively. The performance of screening was not improved by the addition of free β-hCG or the free β-hCG/PlGF ratio. Conclusion: Screening by maternal characteristics and serum PlGF at 30-33 weeks could identify most pregnancies that will subsequently develop PE.