title: Maternal functional hemodynamics in the second half of pregnancy: a longitudinal study.
abstract: OBJECTIVE
  Cardiovascular response to passive leg raising (PLR) is useful in assessing preload reserve, but it has not been studied longitudinally during pregnancy. We aimed to investigate gestational age associated serial changes in maternal functional hemodynamics and establish longitudinal reference ranges for the second half of pregnancy.
  
  
  METHODS
  This was a prospective longitudinal study on 98 healthy pregnant women who were examined 3-5 times during 20-40 weeks of gestation (a total of 441 observations). Maternal cardiac function and systemic hemodynamics were assessed at baseline and 90 seconds after PLR using impedance cardiography (ICG). The main outcome measures were gestational age specific changes in ICG-derived variables of maternal cardiovascular function and functional hemodynamic response to PLR.
  
  
  RESULTS
  Hemodynamic response to PLR varied during pregnancy. PLR led to an insignificant increase in stroke volume during 20+0 to 31+6 weeks, but later in gestation the stroke volume was slightly lower at PLR compared to baseline. PLR caused no significant change in cardiac output between 20+0 and 23+6 weeks and a significant decrease after 24+0 weeks. A decrease in heart rate, mean arterial pressure, and cardiac contractility was observed during PLR throughout the second half of pregnancy. Systemic vascular resistance was reduced by PLR up to 32+0 weeks, but increased slightly thereafter.
  
  
  CONCLUSIONS
  Healthy pregnant women appear to have limited preload reserve and reduced cardiac contractility, especially in the third trimester, which makes them vulnerable to fluid overload and cardiac failure.
authors.affiliation: Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT- The Arctic University of Norway and Department of Obstetrics and Gynecology, University Hospital of Northern Norway, Tromsø, Norway.
authors.forename: Åse
authors.initials: Å
authors.lastname: Vårtun
authors.affiliation: Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT- The Arctic University of Norway and Department of Obstetrics and Gynecology, University Hospital of Northern Norway, Tromsø, Norway.
authors.forename: Kari
authors.initials: K
authors.lastname: Flo
authors.affiliation: Department of Community Medicine, Faculty of Health Sciences, UiT- The Arctic University of Norway, Tromsø, Norway.
authors.forename: Tom
authors.initials: T
authors.lastname: Wilsgaard
authors.affiliation: Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT- The Arctic University of Norway and Department of Obstetrics and Gynecology, University Hospital of Northern Norway, Tromsø, Norway; Department of Clinical Sciences, Intervention and Technology, Karolinska Institute, Stockholm, Sweden.
authors.forename: Ganesh
authors.initials: G
authors.lastname: Acharya
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology*; D005260:Female; D005865:Gestational Age; D018475:Head-Down Tilt; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007866:Leg; D008137:Longitudinal Studies; D009200:Myocardial Contraction / Q000502:physiology; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D012016:Reference Values; D013318:Stroke Volume / Q000502:physiology*; D014655:Vascular Resistance / Q000502:physiology*