title: Fetal heart rate variability reveals differential dynamics in the intrauterine development of the sympathetic and parasympathetic branches of the autonomic nervous system.
abstract: The aim of this study was to investigate the hypothesis that fetal beat-to-beat heart rate variability (fHRV) displays the different time scales of sympatho-vagal development prior to and after 32 weeks of gestation (wks GA). Ninety-two magnetocardiograms of singletons with normal courses of pregnancy between 24 + 1 and 41 + 6 wks GA were studied. Heart rate patterns were either quiet/non-accelerative (fHRP I) or active/accelerative (fHRP II) and recording quality sufficient for fHRV. The sample was divided into the GA groups <32 wks GA/>32 wks GA. Linear parameters of fHRV were calculated: mean heart rate (mHR), SDNN and RMSSD of normal-to-normal interbeat intervals, power in the low (0.04-0.15 Hz) and high frequency range (0.15-0.4 Hz) and the ratios SDNN/RMSSD and LF/HF as markers for sympatho-vagal balance. fHRP I is characterized by decreasing SDNN/RMSSD, LF/HF and mHR. The decrease is more pronounced <32 wks GA. Beyond that GA SDNN/RMSSD is predominantly determined by RMSSD during fHRP I and by SDNN during fHRP II. In contrast to fHRP I, during fHRP II, mHR is positively correlated to SDNN/RMSSD instead of SDNN >32 wks GA. LF/HF increases in fHRP II during the first half of the third trimester. Non-accelerative fHRP are indicative of parasympathetic dominance >32 wks GA. In contrast, the sympathetic accentuation during accelerative fHRP is displayed in the interrelations between mHR, SDNN and SDNN/RMSSD. Prior to 32 wks GA, fHRV reveals the increasing activity of the respective branches of the autonomic nervous system differentiating the types of fHRP.
authors.affiliation: Department of Obstetrics, University Hospital, Friedrich Schiller University of Jena, Jena, Germany. Uwe.Schneider@med.uni-jena.de
authors.forename: U
authors.initials: U
authors.lastname: Schneider
authors.forename: E
authors.initials: E
authors.lastname: Schleussner
authors.forename: A
authors.initials: A
authors.lastname: Fiedler
authors.forename: S
authors.initials: S
authors.lastname: Jaekel
authors.forename: M
authors.initials: M
authors.lastname: Liehr
authors.forename: J
authors.initials: J
authors.lastname: Haueisen
authors.forename: D
authors.initials: D
authors.lastname: Hoyer
mesh_terms: D005260:Female; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D010275:Parasympathetic Nervous System / Q000196:embryology* / Q000502:physiology*; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D013564:Sympathetic Nervous System / Q000196:embryology* / Q000502:physiology*; D014630:Vagus Nerve / Q000196:embryology / Q000502:physiology