Maternal serum placental growth factor at 12, 22, 32 and 36 weeks' gestation in screening for pre-eclampsia

Abstract

Objective To examine the distribution of maternal serum placental growth factor (PlGF) at 12, 22, 32 and 36 weeks' gestation in singleton pregnancies which develop pre-eclampsia (PE) and examine the performance of this biomarker in screening for PE. Methods Serum PlGF was measured in 40 212 cases at 11-13 weeks, in 10 282 cases at 19-24 weeks, in 10 400 at 30-34 weeks and 4043 at 35-37 weeks. Bayes' theorem was used to combine the a-priori risk from maternal characteristics and medical history with serum PlGF. The performance of screening for PE requiring delivery < 32, at 32 + 0 to 36 + 6 and ≥ 37 weeks' gestation was estimated. Results In pregnancies that developed PE, serum PlGF was decreased and the separation in multiples of the median (MoM) values from normal was greater with earlier, compared to later, gestational age at which delivery for PE became necessary. Additionally, the slope of the regression lines of PlGF MoM with gestational age at delivery in pregnancies that developed PE increased with advancing gestational age at screening. The detection rates (DRs), at a false-positive rate (FPR) of 10%, for PE delivering < 32 weeks were 79% and 97% with screening at 12 and 22 weeks, respectively. The DRs for PE delivering at 32 + 0 to 36 + 6 weeks were 57%, 65% and 90% with screening at 12, 22 and 32 weeks. The DRs for PE delivering ≥ 37 weeks were 40%, 37%, 54% and 64% with screening at 12, 22, 32 and 36 weeks, respectively. Conclusions The performance of combined screening with maternal factors, medical history and PlGF is superior in screening for early, compared to late, PE and improves with advancing gestational age at screening.