title: Prenatal RR fluctuations dynamics: detecting fetal short-range fractal correlations.
abstract: OBJECTIVE
  Several studies have suggested that the analysis of heart rate variability (HRV) during gestation provides indications of the development or maturation of fetal cardiovascular regulatory mechanisms. In this study, we evaluate the existence of short-range fractal-like correlations in fetal RR fluctuations data from the second half of human gestation.
  
  
  METHODS
  Fifty-six short-term abdominal ECG recordings were obtained from low-middle-risk pregnant women. Gestational age varied from estimated 21 weeks to term. For comparison, RR-interval data of 51 healthy adults were also analysed.
  
  
  RESULTS
  Principal findings along the gestational period explored were the existence of fractal RR dynamics in prenatal fetal data as revealed by the short-range scaling exponent alpha(1). No significant differences of alpha(1) (p = 0.4770) were found between fetal (median 1.2879) and adult data (median 1.3214), either between the fetal cases before or after 24 weeks (p = 0.6116) despite observing more variation at early stages. However, fetal RR data did involve lower magnitude in comparison with adults as we found significant differences in pNN20 and SDNN values.
  
  
  CONCLUSIONS
  The fetal short-range fractal behaviour of RR data could then be linked to the functional development of the parasympathetic activity, which appears to become manifested before 21 weeks of gestation.
authors.affiliation: Electrical Engineering Department, Universidad Autónoma Metropolitana-Izt., Mexico City, Mexico. mrop@xanum.uam.mx
authors.forename: M R
authors.initials: MR
authors.lastname: Ortiz
authors.forename: S D
authors.initials: SD
authors.lastname: Aguilar
authors.forename: J
authors.initials: J
authors.lastname: Alvarez-Ramirez
authors.forename: A
authors.initials: A
authors.lastname: Martínez
authors.forename: C
authors.initials: C
authors.lastname: Vargas-Garcia
authors.forename: R
authors.initials: R
authors.lastname: González-Camarena
authors.forename: J C
authors.initials: JC
authors.lastname: Echeverría
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015148:Cardiotocography / Q000379:methods*; D002320:Cardiovascular Physiological Phenomena; D004562:Electrocardiography; D005260:Female; D005318:Fetal Heart / Q000502:physiology*; D017709:Fractals; D005865:Gestational Age; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*