title: Prediction of small-for-gestational-age neonates: screening by uterine artery Doppler and mean arterial pressure at 19-24 weeks.
abstract: OBJECTIVE
  To investigate the potential value of uterine artery (UtA) pulsatility index (PI) and mean arterial pressure (MAP) at 19-24 weeks' gestation, in combination with maternal characteristics and medical history and fetal biometry in the prediction of delivery of small-for-gestational-age (SGA) neonates in the absence of pre-eclampsia (PE) and to examine the potential value of such assessment in deciding whether the third-trimester scan should be performed at 32 and/or 36 weeks' gestation.
  
  
  METHODS
  This was a screening study in 63 975 singleton pregnancies, including 3702 (5.8%) that delivered SGA neonates with birth weight < 5(th) percentile (SGA < 5(th) ) in the absence of PE. Multivariable logistic regression analysis was used to determine if screening by a combination of maternal factors, fetal head circumference (HC), abdominal circumference (AC), femur length (FL), UtA-PI and MAP had significant contribution in predicting SGA neonates. A model was developed to select gestational age for the third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks.
  
  
  RESULTS
  The detection rates (DRs) of combined screening by maternal factors, fetal biometry and UtA-PI at 19-24 weeks were 90%, 68% and 44% for SGA < 5(th) delivering < 32, 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. The performance of screening was not improved by the addition of MAP. The DR of SGA < 5(th) delivering at 32-36 weeks improved from 68% to 90% with screening at 32 rather than at 19-24 weeks. Similarly, the DR of SGA < 5(th) delivering ≥ 37 weeks improved from 44% with screening at 19-24 weeks to 59% and 76% when screening at 32 and 36 weeks, respectively. In a hypothetical model, it was estimated that if the desired objective of prenatal screening is to predict about 80% of the cases of SGA < 5(th) , it would be necessary to select 17% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 38% to be reassessed at 36 weeks; 62% would not require a third-trimester scan.
  
  
  CONCLUSIONS
  Prenatal prediction of a high proportion of SGA neonates necessitates the undertaking of screening in the third trimester of pregnancy in addition to assessment in the second trimester, and the timing of such screening, at 32 and/or 36 weeks, should be contingent on the results of the assessment at 19-24 weeks.
authors: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
authors: C
authors: C
authors: Lesmes
authors: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
authors: D M
authors: DM
authors: Gallo
authors: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
authors: Y
authors: Y
authors: Saiid
authors: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
authors: L C
authors: LC
authors: Poon
authors: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
authors: K H
authors: KH
authors: Nicolaides
mesh_terms: D000328:Adult; D062186:Arterial Pressure; D000066491:Clinical Decision-Making; D003661:Decision Support Techniques; D005189:False Positive Reactions; D005260:Female; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D016015:Logistic Models; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D011673:Pulsatile Flow; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal / Q000379:methods*; D055988:Uterine Artery / Q000000981:diagnostic imaging* / Q000502:physiology
keywords: mean arterial pressure; pre-eclampsia; pyramid of antenatal care; second-trimester screening; small-for-gestational age; uterine artery Doppler