title: Mid-pregnancy fetal biometry, uterine artery Doppler indices and maternal demographic characteristics: role in prediction of small-for-gestational-age birth.
abstract: BACKGROUND
  The aim of this study was to evaluate the role of mid-trimester fetal biometry, uterine artery Doppler indices and maternal demographics in prediction of small-for-gestational-age (SGA) birth.
  
  
  METHODS
  We conducted a retrospective cohort study in a single referral center. The study included 23 894 singleton pregnancies scanned between 19 and 24 weeks of gestation. Maternal demographics included age, body mass index and ethnicity. Fetal biometry, birthweight and uterine artery pulsatility index values were converted into centiles. Multivariable logistic regression analysis was performed and the predictive accuracy was assessed using receiver operating characteristic curve analysis. The main outcome measure was prediction of delivery of preterm and term SGA neonates defined as a birthweight in the lowest centile groups (<10th, <5th and <3rd centiles).
  
  
  RESULTS
  Maternal ethnicity, fetal biometry and uterine artery Doppler indices were significantly associated with the risk of SGA <5th centile (p < 0.01). Maternal factors or fetal biometry alone showed poor to moderate performance in prediction of term and preterm SGA <5th centile at a 10% false-positive rate. Uterine artery pulsatility index alone was able to predict 25, 60 and 77% of SGA <5th centile delivering at >37, <37 and <32 weeks of gestation respectively at a 10% false-positive rate; maternal factors, fetal biometry and uterine artery Doppler combined detected 40, 66 and 89% of term, preterm and very preterm SGA <5th centile at a 10% false-positive rate.
  
  
  CONCLUSIONS
  Second-trimester screening can identify the majority of pregnancies at high risk of SGA birth and showed a higher performance for earlier gestational ages at birth and lower birthweight centiles.
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, UK.
authors.forename: Alessandra
authors.identifier: http://orcid.org/0000-0002-6353-9383
authors.initials: A
authors.lastname: Familiari
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, UK.
authors.forename: Amar
authors.identifier: http://orcid.org/0000-0002-2171-5377
authors.initials: A
authors.lastname: Bhide
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, UK.
authors.forename: Maddalena
authors.identifier: http://orcid.org/0000-0002-1304-7575
authors.initials: M
authors.lastname: Morlando
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, UK.
authors.forename: Carolina
authors.identifier: http://orcid.org/0000-0001-7503-0034
authors.initials: C
authors.lastname: Scala
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, UK.
authors.forename: Asma
authors.identifier: http://orcid.org/0000-0003-2802-7670
authors.initials: A
authors.lastname: Khalil
authors.affiliation: Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, UK.
authors.forename: Basky
authors.identifier: http://orcid.org/0000-0002-5531-4301
authors.initials: B
authors.lastname: Thilaganathan
mesh_terms: D000328:Adult; D001699:Biometry / Q000379:methods*; D001724:Birth Weight; D015992:Body Mass Index; D003710:Demography; D005006:Ethnicity; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008423:Maternal Age; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D012189:Retrospective Studies; D012307:Risk Factors; D014463:Ultrasonography; D055988:Uterine Artery / Q000000981:diagnostic imaging*
keywords: Small-for-gestational age; fetal biometry; maternal demographics; prediction of high risk pregnancies; second-trimester screening; uterine artery Doppler