title: Mean arterial pressure at 12, 22, 32 and 36 weeks' gestation in screening for pre-eclampsia.
abstract: OBJECTIVE
  To examine the distribution of mean arterial pressure (MAP) 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
  MAP was measured in 77 343 cases at 11-13 weeks, in 31 120 cases at 19-24 weeks, in 29 802 at 30-34 weeks and 5543 at 35-37 weeks. Bayes' theorem was used to combine the a-priori risk from maternal characteristics and medical history with MAP. 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, MAP was increased and the separation in multiples of the median (MoM) values from normal was greater with an earlier, compared to later, gestational age at which delivery for PE became necessary. Additionally, the slope of the regression lines of MAP MoM with gestational age at delivery in pregnancies that developed PE increased with advancing gestational age at screening. The detection rate (DR), at a false-positive rate of 10%, for PE delivering < 32 weeks was 66% and 72% with screening at 12 and 22 weeks, respectively. The DR for PE delivering at 32 + 0 to 36 + 6 weeks was 54%, 56% and 81% with screening at 12, 22 and 32 weeks. The DR for PE delivering ≥ 37 weeks was 45%, 43%, 49% and 59% with screening at 12, 22, 32 and 36 weeks, respectively.
  
  
  CONCLUSIONS
  The performance of combined screening with maternal factors and MAP is superior in screening for early, compared to late, PE and, to a certain extent, improves with advancing gestational age at screening. 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: A
authors.initials: A
authors.lastname: Tayyar
authors.affiliation: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
authors.forename: K
authors.initials: K
authors.lastname: Krithinakis
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: D000328:Adult; D062186:Arterial Pressure; D001499:Bayes Theorem; D005260:Female; D005865:Gestational Age; D006801:Humans; D011225:Pre-Eclampsia / Q000175:diagnosis*; D011247:Pregnancy; D012680:Sensitivity and Specificity; D055988:Uterine Artery / Q000502:physiology*
keywords: Bayes' theorem; impaired placentation; mean arterial pressure; pre-eclampsia; pyramid of pregnancy care