title: Maternal serum alpha-fetoprotein at 12, 22 and 32 weeks' gestation in screening for pre-eclampsia.
abstract: To examine the distribution of maternal serum alpha-fetoprotein (AFP) at 12, 22 and 32 weeks' gestation in singleton pregnancies which develop pre-eclampsia (PE) and examine the performance of this biomarker in screening for PE.
  
  
  
  Serum AFP was measured in 17 071 cases at 11-13 weeks, in 8583 cases at 19-24 weeks and 8609 cases at 30-34 weeks' gestation. Bayes' theorem was used to combine the a-priori risk from maternal characteristics and medical history with AFP. The performance of screening for PE requiring delivery < 32, at 32 + 0 to 36 + 6, < 37 and ≥ 37 weeks' gestation was estimated.
  
  
  
  In pregnancies that developed PE, serum AFP multiples of the median (MoM) was increased at 11-13 and 19-24 weeks' gestation, but not at 30-34 weeks, and the values were inversely related to gestational age at delivery. Combined screening with maternal factors and serum AFP improved the prediction provided by maternal factors alone for PE delivering < 37 weeks, but not for PE delivering ≥ 37 weeks. The performance of screening for preterm PE was better at 19-24 weeks than at 11-13 weeks and the detection rate (DR) for a given false-positive rate (FPR) was higher for PE delivering < 32 weeks than for PE delivering at 32 + 0 to 36 + 6 weeks. The DRs, at 10% FPR, of combined screening at 11-13 weeks for PE delivering < 32 and at 32 + 0 to 36 + 6 weeks were 54% and 45%, respectively, and these improved to 72% and 53% with screening at 19-24 weeks.
  
  
  
  Measurement of serum AFP at 11-13 and 19-24 weeks' gestation improves the prediction of preterm PE provided by maternal factors alone. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.
authors.affiliation: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
authors.forename: F E
authors.initials: FE
authors.lastname: Bredaki
authors.affiliation: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Matalliotakis
authors.affiliation: Institute of Health Research, University of Exeter, Exeter, UK.
authors.forename: A
authors.initials: A
authors.lastname: Wright
authors.affiliation: Institute of Health Research, University of Exeter, Exeter, UK.
authors.forename: D
authors.initials: D
authors.lastname: Wright
authors.affiliation: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
authors.forename: K H
authors.initials: KH
authors.lastname: Nicolaides
mesh_terms: D001499:Bayes Theorem; D015415:Biomarkers / Q000097:blood; D005260:Female; D005865:Gestational Age; D006801:Humans; D011225:Pre-Eclampsia / Q000097:blood / Q000175:diagnosis*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011264:Pregnancy Trimesters / Q000097:blood*; D047928:Premature Birth / Q000097:blood / Q000209:etiology; D011296:Prenatal Diagnosis / Q000379:methods*; D011446:Prospective Studies; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: D015415:Biomarkers; D000509:alpha-Fetoproteins
keywords: Bayes' theorem; alpha fetoprotein; impaired placentation; pre-eclampsia; pyramid of pregnancy care; screening