title: The relationship between age-related heart rate changes and developing brain function: a model of anencephalic human fetuses in utero.
abstract: We attempted to identify the brain segment which controls heart rate changes in human fetuses with advancing gestation. Twelve anencephalic and 165 normal fetuses (control-group fetuses) between 25-32 weeks' gestation were studied. The instantaneous fetal heart rate (FHR) data were obtained from each fetus for a continuous 90-120 min period, using an external cardiotocograph. Calculations included the 'individual probability distribution matrices' in which the FHRs at 1 beat/min intervals between 110 and 180 beats/min, the beat-to-beat differences (DFHRs) between +/- 5 beats/min and the probability values were arranged in rows, columns and the corresponding elements, respectively. Using 2-gestational-week intervals probability distribution matrices (age-group probability distribution matrices) obtained from 335 normal fetuses in our previous study as a reference, the difference between a given 'individual probability distribution matrix' and the corresponding age-group probability distribution matrix' was quantified as the 'difference rate' according to the formula in the text. From 25-26 to 27-28 weeks' gestation, the 'difference rates' in four anencephalic fetuses, with only the spinal cord preserved, were significantly higher in value than those of control-group fetuses, whereas the rates in four fetuses with both the spinal cord and medulla oblongata preserved, indicated no significant differences. From 29-30 to 31-32 weeks' gestation, the rates of the four fetuses with the spinal cord and medulla oblongata preserved, showed significant differences from the control-group fetuses. These findings suggest that there is a critical period between 27-28 and 29-30 weeks' gestation with regard to the developing brain function pertaining to FHR changes. In the early stage, the medulla oblongata plays a role in FHR changes, whereas, in the latter stage, the brain cephalad to the medulla also appears to take on the role of FHR regulator.
authors.affiliation: Department of Gynecology and Obstetrics Faculty of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yoshizato
authors.forename: T
authors.initials: T
authors.lastname: Koyanagi
authors.forename: T
authors.initials: T
authors.lastname: Takashima
authors.forename: S
authors.initials: S
authors.lastname: Satoh
authors.forename: K
authors.initials: K
authors.lastname: Akazawa
authors.forename: H
authors.initials: H
authors.lastname: Nakano
mesh_terms: D000757:Anencephaly / Q000196:embryology* / Q000503:physiopathology; D001921:Brain / Q000196:embryology* / Q000502:physiology; D005260:Female; D005865:Gestational Age; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D008297:Male; D008526:Medulla Oblongata / Q000196:embryology / Q000502:physiology; D011247:Pregnancy; D013116:Spinal Cord / Q000196:embryology / Q000502:physiology