title: Reference values of maternal ophthalmic artery doppler variables in the first trimester of normal pregnancy.
abstract: BACKGROUND
  The aim of this study was to establish normative data for ophthalmic artery Doppler variables in the first trimester of normal pregnancy.
  
  
  METHODS
  Maternal ophthalmic artery Doppler signals were recorded in 409 singleton pregnancies at 11-14 weeks' gestation, in mothers presenting consecutively for routine antenatal care. Pulsatility and resistance indices (PI, RI), peak systolic velocity (PSV), first peak diastolic velocity (PD1), and peak ratio (PR) were measured. Quartile regression was used to estimate reference ranges in the late first trimester of pregnancy.
  
  
  RESULTS
  Mean ± SD values for maternal ophthalmic artery Doppler parameters between 11 and 14 weeks' gestation were RI = 0.81 ± 0.12, PI = 2.06 ± 0.57, PSV = 36.41 ± 12.1, PD1 = 21.07 ± 7.62, and PR = 0.58 ± 0.11. All clinical and Doppler variables were normally distributed. PD1 values were higher in patients who smoked, and in those with diabetes or a history of pre-eclampsia. PR values were higher in patients with diabetes and chronic hypertension, and lower in the nulliparous; these values declined as gestation advanced from 11 to 14 weeks, whereas the other variables remained unchanged.
  
  
  CONCLUSIONS
  We provide reference values for maternal ophthalmic artery Doppler variables in the first trimester of normal pregnancy.
authors.affiliation: Department of Public Health, State University of Ceará, Fortaleza, Ceará, Brazil.
authors.forename: Júlio Augusto Gurgel
authors.initials: JA
authors.lastname: Alves
authors.forename: Bruna
authors.initials: B
authors.lastname: Yang
authors.forename: Paulo Cesar Praciano
authors.initials: PC
authors.lastname: de Sousa
authors.forename: Sammya
authors.initials: S
authors.lastname: Bezerra Maia E Holanda Moura
authors.forename: Stefan
authors.initials: S
authors.lastname: Kane
authors.forename: Fabrício
authors.initials: F
authors.lastname: da Silva Costa
mesh_terms: D000293:Adolescent; D000328:Adult; D001938:Brazil; D015331:Cohort Studies; D005260:Female; D006801:Humans; D009880:Ophthalmic Artery / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D012016:Reference Values; D018617:Ultrasonography, Doppler, Pulsed / Q000379:methods*; D055815:Young Adult
keywords: Doppler ultrasonography; first-trimester pregnancy; ophthalmic artery; reference range