title: Early maturation of sinus rhythm dynamics in high-risk fetuses.
abstract: OBJECTIVE
  The purpose of this study was to compare cardiac dynamics of high-risk and low-risk fetuses using beat to beat variability.
  
  
  METHODS
  This study obtained 214 fetal magnetocardiography recordings from a group of high-risk fetuses with maternal conditions associated with placental insufficiency with the risk of developing intrauterine growth restriction or were already diagnosed with intrauterine growth restriction. For purpose of comparison, another 136 recordings were obtained from low-risk fetuses. The cardiac beat-to-beat intervals computed as RR intervals were analyzed from both groups using the mean and median interval, standard deviation of normal-to-normal intervals, root mean square of the successive differences, and the fraction of the normal-to-normal intervals (pNNx) that differ by more than the chosen tolerance level of 'x' milliseconds from the previous normal-to-normal intervals. Tests for significance between high-risk and low-risk fetuses were calculated using an independent samples t test within the following gestational age groups, 27-30 weeks, 31-35 weeks, and 36-40 weeks.
  
  
  RESULTS
  The root mean square of the successive differences, and the pNNx showed a significant difference between the low-risk and high-risk fetuses in the 31-35-week and the 36-40-week divisions. In the 31-35-week age division, low-risk fetuses had significantly lower root mean square of the successive differences, and pNN values than the high risk, but in the 36-40-week division, the low-risk fetuses had significantly higher root mean square of the successive differences, and pNN values.
  
  
  CONCLUSIONS
  Cardiac dynamics for fetuses of mothers at risk for placental insufficiency mature quicker than fetuses not at risk for placental insufficiency.
authors.affiliation: Graduate Institute of Technology, University of Arkansas, Little Rock, AR, USA.
authors.forename: R B
authors.initials: RB
authors.lastname: Govindan
authors.forename: Curtis L
authors.initials: CL
authors.lastname: Lowery
authors.forename: J Quaid
authors.initials: JQ
authors.lastname: Campbell
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Best
authors.forename: Pamela
authors.initials: P
authors.lastname: Murphy
authors.forename: Hubert T
authors.initials: HT
authors.lastname: Preissl
authors.forename: Hari
authors.initials: H
authors.lastname: Eswaran
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005317:Fetal Growth Retardation / Q000503:physiopathology; D005865:Gestational Age; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D053798:Magnetocardiography; D008875:Middle Aged; D010927:Placental Insufficiency / Q000503:physiopathology; D011247:Pregnancy; D011256:Pregnancy Outcome; D018566:Pregnancy, High-Risk