Prediction of spontaneous preterm delivery from maternal factors, obstetric history and placental perfusion and function at 11-13 weeks

Objective To develop a model for prediction of spontaneous delivery before 34 weeks based on maternal factors, placental perfusion and function at 11-13 weeks' gestation. Methods Two groups of studies: first, screening study of maternal characteristics, serum pregnancy-associated plasma protein-A (PAPP-A), free beta-human chorionic gonadotrophin (beta-hCG) and uterine artery pulsatility index (PI). Second, case-control studies of maternal serum or plasma concentration of placental growth factor (PlGF), placental protein 13 (PP13), a disintegrin and metalloprotease 12 (ADAM12), inhibin-A and activin-A. Regression analysis was used to develop a model for the prediction of spontaneous early delivery. Results Spontaneous early delivery occurred in 365 (1.1%) of the 34 025 pregnancies. A model based on maternal factors could detect 38.2% of the preterm deliveries in women with previous pregnancies at or beyond 16 weeks and 18.4% in those without, at a false positive rate (FPR) of 10%. In the preterm delivery group, compared with unaffected pregnancies there were no significant differences in the markers of placental perfusion or function, except for PAPP-A which was reduced. Conclusions Patient-specific risk of preterm delivery is provided by maternal factors and obstetric history. Placental perfusion and function at 11-13 weeks are not altered in pregnancies resulting in spontaneous early delivery. Copyright (C) 2011 John Wiley & Sons, Ltd.