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

Toshiaki Suzuki, Yoshitaka Kimura, Jun Murotsuki, Takashi Murakami, Shigeki Uehara, Kunihiro Okamura

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


OBJECTIVE: This study describes a 24-hour assay of autonomic nervous system activity in human fetuses with the use of a power spectral analysis of heartbeat intervals. STUDY DESIGN: The study included 6 normal fetuses and 11 growth-restricted fetuses, 3 of which were hypoxemic. Fetal heartbeats were continuously recorded for 24 hours, and a power spectral analysis was performed on the beat interval data. A low frequency domain of beat intervals was identified (0.025-0.125 cycles/beat) and evaluated at regular intervals over the 24-hour period. The cosinor method was used to detect rhythmic fluctuations in the resulting low frequency areas. The same procedures were also performed with the mothers of the fetuses. RESULTS: We observed 2 diurnal rhythms of heartbeat activity (1 with a 12-hour period and another with a 24-hour period) in the normal and growth-restricted fetuses without hypoxemia. In contrast, these rhythms were not observed in the hypoxemic fetuses. In the mothers, only the 24-hour rhythm was observed. CONCLUSION: The 12-hour cycle of autonomic nervous activity is present in normal fetuses.

Original languageEnglish
Pages (from-to)1247-1252
Number of pages6
JournalAmerican Journal of Obstetrics and Gynecology
Issue number5
Publication statusPublished - 2001


  • Autonomic nervous system
  • Biorhythm
  • Fetus
  • Spectral analysis

ASJC Scopus subject areas

  • Obstetrics and Gynaecology


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