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Updated: May 15, 2026
In utero Measurement of Heart Rate in Mouse by Noninvasive M-mode Echocardiography
Published on: November 22, 2013
Correlation between regular mouthing movements and heart rate patterns during non-rapid eye movement periods in
Yuka Otera1, Seiichi Morokuma, Kotaro Fukushima
1Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. ohtera@med.kyushu-u.ac.jp
Background:
Regular mouthing movements (RMMs) are observed during fetal non-rapid eye movement (NREM) periods.
Aim:
To determine the correlation between RMM and fetal heart rate (FHR) patterns during NREM periods.
Study Design:
Fetal eye and mouth movements and FHR patterns were observed and recorded.
Subjects:
50 normal singleton pregnancies between 32 and 40 weeks of gestation.
Outcome Measures:
Changes in the power spectrum ratio of 3-minute blocks of RMM clusters, FHR with RMM clusters (HR+), and FHR without RMM clusters (HR-) were calculated at a frequency band of 0.02 Hz among 3 gestational age groups: group 1, 32-34 weeks gestation; group 2, 35-37 weeks gestation; group 3, 38-40 weeks gestation. We calculated the percentage of cases showing dominant peak ratios of RMM and HR+ in the same frequency band, the maximum correlation coefficient, and its lag time.
Results:
In group 3, the dominant peaks of both RM and HR+ were present at the same frequency band, 0.06-0.08 Hz; this was not seen in the other groups' relative power spectral patterns. The percentage of cases showing dominant peaks of RMM and HR+ in the same frequency band increased with advancing gestational age. The maximum correlation coefficient in groups 1 (0.28 ± 0.11) and 3 (0.45 ± 0.14) differed significantly (p<0.05).
Conclusions:
The correlation between RMM and FHR patterns became stronger, and their rhythmicity was similar, from 38 to 40 gestational weeks, suggesting that a common center starts to govern both patterns at approximately 38 weeks gestation.
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