title: Alterations in irregular and fractal heart rate behavior in growth restricted fetuses.
abstract: OBJECTIVE
  To determine whether irregularity, and short- and long-term fractal correlation reflecting smoothness of heart rate behavior are changed in intrauterine growth restricted fetuses.
  
  
  METHODS
  Fetal heart rate data of 192 normal fetuses and 86 intrauterine growth restricted fetuses between 31 and 42 weeks of gestation were studied. Approximate entropy to quantify irregularity, and short-term (< or =80 beats, alpha1) and long-term (>80 beats, alpha2) fractal scaling exponents to quantify the short- and long-term fractal correlation were calculated.
  
  
  RESULTS
  In the intrauterine growth restricted fetuses, the approximate entropy was significantly lower (P<0.001). The alpha2 value was significantly higher (P=0.0001) than in the normal fetuses, which performed better (F=34.2, P<0.0001) than other heart rate variability indexes in differentiating the intrauterine growth restricted fetuses from the normal fetuses in stepwise discriminant analysis.
  
  
  CONCLUSIONS
  Compared to normal fetuses, intrauterine growth restricted fetuses show a difference in that the irregularity of the fetal heart is decreased. A more apparent difference is that the long-term fractal correlation of the fetal heart is increased and the fetal heart is smoother in the long-term scale.
authors.affiliation: Department of Pediatric Cardiology, Hanyang University School of Medicine, 17 Haengdang-dong Sungdong-ku, 133-792, Seoul, South Korea. mkyumm@email.hanyang.ac.kr
authors.forename: M K
authors.initials: MK
authors.lastname: Yum
authors.forename: E Y
authors.initials: EY
authors.lastname: Park
authors.forename: C R
authors.initials: CR
authors.lastname: Kim
authors.forename: J H
authors.initials: JH
authors.lastname: Hwang
mesh_terms: D000328:Adult; D001724:Birth Weight; D005260:Female; D005317:Fetal Growth Retardation / Q000503:physiopathology*; D005865:Gestational Age; D006340:Heart Rate, Fetal; D006801:Humans; D008433:Mathematics; D011247:Pregnancy