Heart Rate Changes During the First Hour of Life

Heart rate in fetuses and neonates in normal conditions and with mild depression

“…Our results suggest that BFHR follows a stable patter n during the 90 minutes preceding delivery, at values which agree with those already described (Figs. l and 2) [11]. The individual study of these cases shows a certain dependence between values of BFHR at the end of labor, and the preceding ones (Fig.…”

“…During delivery, in response to the different acting Stimuli, marked fetal bradycardias are usually produced. Immediately after birth, and if pulmonary Ventilation Starts normally, neonatal heart rate rises significantly during the first minutes of life, and then falls gradually until it becomes stabilized at values similar to those of fetal heart rate [4,5,6,11,15]. In the present study the results obtained in vigorous and mildly depressed newborns [l, 2,3,13] by the continuous recording of fetal heart rate during labor and of neonatal heart rate during 90 minutes after birth, are presented.…”

Effect of Method of Delivery on Heart Rate Pattern in the Early Newborn

“…This premise remains speculative, since NHR levels in these studies correlated poorly with 1-minute Apgar scores, umbilical cord pH levels, and neonatal blood pressures.~ 2 An alternative explanation for the increased heart rate during the early newborn period is based on the manner in which the neonate responds to the release of catecholamines during delivery into a cold environment. Recent studies of the newborns dog and 'sheep suggest that while cardiac beta receptor maturation is complete, neurogenic control of NHR is incomplete in the first days after birth.6,7 Since norepinephrine is primarily inactivated through uptake and binding in sympathetic nerves, incomplete neurogenic development could result in reduced inactivation and therefore higher circulating levels of endogenous sympathetic amines from adrenal or extradrenal sources.…”