First-trimester maternal serum pregnancy-associated plasma protein-A and pre-eclampsia.

OBJECTIVES To examine the relationship between low maternal serum pregnancy-associated plasma protein-A (PAPP-A) and uterine artery pulsatility index (UtA-PI) at 11+0 to 13+6 weeks with subsequent development of pre-eclampsia (PE). METHODS UtA-PI and serum PAPP-A were measured in women attending for routine care at 11+0 to 13+6 weeks of gestation. In the population, 156 (1.9%) women developed PE, including 32 (0.4%) in whom delivery was before 34 weeks (early PE) and 124 (1.5%) with delivery at 34 weeks or more (late PE); 7895 (98.1%) women had no PE. Regression analysis was used to examine which of the factors amongst maternal characteristics, log PAPP-A multiples of the median (MoM) and log UtA-PI MoM contributed to the prediction of PE. RESULTS The median PAPP-A MoM was 1.002 (interquartile range (IQR), 0.685-1.411) in the unaffected group, 0.555 (IQR, 0.463-0.922) in early PE and 0.911 (IQR, 0.580-1.247) in late PE. Serum PAPP-A was below the 5th centile in 21.9% of early PE and 6.5% of late PE cases. The PAPP-A-related patient-specific risk for PE was strongly influenced by maternal characteristics. There was a significant association between log UtA-PI MoM and log PAPP-A MoM (P=0.001), and the detection rate of screening for PE by maternal variables and UtA-PI was not improved by inclusion of PAPP-A. Regression analysis was used to establish tables that allow modification of the maternal history and PAPP-A-related patient-specific risk for PE by the measurement of UtA-PI. CONCLUSIONS Low PAPP-A is a marker for subsequent development of PE. The PAPP-A-related patient-specific risk for PE can be modified by the measurement of UtA-PI.