title: Socioeconomic inequalities in placental vascular resistance: a prospective cohort study.
abstract: OBJECTIVE
  To examine the association between socioeconomic position (SEP) and umbilical and uterine placental resistance indices in the second and third trimester, and to what extent this could be explained by lifestyle-related behaviors.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Rotterdam, the Netherlands.
  
  
  METHODS
  7,033 pregnant women of mean age (± standard deviation) 29.9 (±5.2) years.
  
  
  METHODS
  None.
  
  
  METHODS
  Uterine artery resistance index (UARI) and umbilical artery pulsatility index (UAPI) in second and third trimester measured with Doppler ultrasound.
  
  
  RESULTS
  Third-trimester UARI and both second- and third-trimester UAPI were statistically significantly higher for women with lower educational levels as compared with those with higher educational levels. Educational level was strongly associated with the risk of continuously high levels of UARI and UAPI from second to third trimester of pregnancy. Notching was not associated with SEP. Smoking was a significant contributor to the association of SEP and increased placental resistance indices; body mass index, folic acid supplementation use, and alcohol use were not.
  
  
  CONCLUSIONS
  Women from low socioeconomic subgroups have higher placental resistance indices, which may cause a higher prevalence of pregnancy complications. This was mainly explained by maternal smoking during pregnancy.
authors.affiliation: The Generation R Study Group, Erasmus Medical Center, Rotterdam, the Netherlands; Department of Public Health, Erasmus Medical Center, Rotterdam, the Netherlands. Electronic address: s.bouthoorn@erasmusmc.nl.
authors.forename: Selma H
authors.initials: SH
authors.lastname: Bouthoorn
authors.affiliation: Department of Public Health, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: van Lenthe
authors.affiliation: The Generation R Study Group, Erasmus Medical Center, Rotterdam, the Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands; Department of Pediatrics, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Romy
authors.initials: R
authors.lastname: Gaillard
authors.affiliation: The Generation R Study Group, Erasmus Medical Center, Rotterdam, the Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.affiliation: Department of Gynecology, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Eric A P
authors.initials: EA
authors.lastname: Steegers
authors.affiliation: The Generation R Study Group, Erasmus Medical Center, Rotterdam, the Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands; Department of Pediatrics, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Vincent W V
authors.initials: VW
authors.lastname: Jaddoe
authors.affiliation: Department of Public Health, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Hein
authors.initials: H
authors.lastname: Raat
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D010920:Placenta / Q000098:blood supply* / Q000473:pathology*; D011159:Population Surveillance / Q000379:methods; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis* / Q000191:economics* / Q000453:epidemiology; D011446:Prospective Studies; D012959:Socioeconomic Factors; D014655:Vascular Resistance / Q000502:physiology*; D055815:Young Adult
keywords: Cohort study; maternal educational level; placental resistance indices; pregnancy complications; smoking during pregnancy