Detection of a biorhythm of human fetal autonomic nervous activity by a power spectral analysis

Spectral analysis of fetal heart rate variability for fetal surveillance: review of the literature

“…Ohta et al studied 26 growth retarded fetuses, corrected for gestational age, and found that the LF power was positively associated with pO 2 and pH in the umbilical vein (16). This was in agreement with Suzuki et al, who found that average LF power was significantly less in growth restricted fetuses with an umbilical venous pO 2 <20 mmHg compared to normal fetuses and growth restricted fetuses without hypoxemia (14).…”

“…The studies were published between 1999 and 2006. All studies were prospective cohort studies 13–18. A total of 527 fetuses (range: 3–334) were described.…”

“…For example, since fetal heart rate variability is positively associated with gestational age and negatively associated with fetal birth weight (13). Further, intra‐individual fluctuations can occur due to changes in behavioural state (37) or due to diurnal rhythms (14). Different cut‐off points should probably be used for different sub‐groups of patients.…”

Neurobehavioral assessment before birth

“…Thus, measurement of variability in heart rate is more informative than mean rate within the normal range [Yeh et al, 1973;Martin, 1978;Dawes et al, 1982;Odendaal, 1990;Street et al, 1991] and a variety of methods for its computation have been proposed. These include root mean square [Dawes et al, 1985], standard deviation [DiPietro et al, 1996b], coefficient of variation [Searle et al, 1988], entropy [Dawes et al, 1992;Fleisher et al, 1997], episodic accelerations [Swartjes et al, 1992] and decelerations [Donker et al, 1993], respiratory sinus arrhythmia [Groome et al, 1994], spectral analysis [Suzuki et al, 2001], and standardized definitions of periods of low and high variation [Street et al, 1991;Nijhuis et al, 2000].…”

Fetal autonomic response to severe acidaemia during labour

“…Previous studies have demonstrated that spectral power in the LF and HF ranges decreased in case of fetal hypoxaemia or acidaemia 10–14 . This was thought to be the result of immaturity or of decompensation of the fetal autonomic nervous system.…”