title: Effect of maternal age on uterine flow impedance.
abstract: OBJECTIVE
  This study was conducted to determine possible maternal age-related changes in uterine artery impedance in normal late pregnancy.
  
  
  METHODS
  In a cross-sectional design study, Doppler velocimetry of the uterine vessels was performed in 884 pregnant women with normal, late, singleton pregnancies. We hypothesized that maternal age is associated with changes in uterine blood flow Doppler parameters. We tested for univariate associations and for an adjusted relationship between these factors using a multivariate model to control for confounders.
  
  
  RESULTS
  We found a statistically significant, nonlinear relationship between mean uterine artery impedance (pulsatility index) and maternal age, with an increase of the pulsatility index in women above the age of 35. This association continued to be significant even when adjusted for gestational age and parity as confounders.
  
  
  CONCLUSIONS
  In normal pregnancy, an increase in uterine artery impedance was noted in women above the age of 35. This finding may be related to the physiologic process of aging and may partly explain why pregnancies in older women are associated with diverse complications more often than those in younger women.
authors.affiliation: Ullevaal University Hospital, Department of Obstetrics and Gynecology, University of Oslo, Kirkeveien 166, N-0407, Oslo, Norway.
authors.forename: Jouko
authors.initials: J
authors.lastname: Pirhonen
authors.forename: Tone Kristin
authors.initials: TK
authors.lastname: Bergersen
authors.forename: Michael
authors.initials: M
authors.lastname: Abdlenoor
authors.forename: Marius
authors.initials: M
authors.lastname: Dubiel
authors.forename: Saemundur
authors.initials: S
authors.lastname: Gudmundsson
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D010298:Parity; D011247:Pregnancy; D012039:Regional Blood Flow; D016216:Ultrasonography, Prenatal; D014599:Uterus / Q000098:blood supply*