Visser G H, Carse E A, Goodman J D, Johnson P
Br J Obstet Gynaecol. 1982 Jan;89(1):50-5. doi: 10.1111/j.1471-0528.1982.tb04634.x.
Fourier analysis was applied to episodes of high and low heart-rate variation in the near-term fetus. The spectral densities of the variations in pulse intervals from 1 to 7 cycles/min, were almost identical with those found by De Haan et al. (1977) in the newborn infant during both active and quiet sleep. A computer programme, designed to separate low and high heart-rate variation episodes in the fetus, identified seven of the eight quiet sleep episodes in four infants. None of the other neonatal behavioural states had low heart-rate variation. It was concluded that, with other published data, there is increasing, although indirect, evidence that low heart-rate variation episodes indicate quiet sleep in the human fetus near term.
傅里叶分析被应用于近期胎儿心率高低变化的各个阶段。1至7次/分钟脉搏间期变化的频谱密度，与德哈恩等人（1977年）在新生儿活跃睡眠和安静睡眠期间所发现的几乎相同。一个旨在区分胎儿心率高低变化阶段的计算机程序，在四名婴儿的八次安静睡眠阶段中识别出了七次。其他新生儿行为状态均不存在低心率变化。得出的结论是，结合其他已发表的数据，越来越多（尽管是间接的）证据表明，低心率变化阶段表明近期人类胎儿处于安静睡眠状态。
