Hoh Jeong-Kyu, Park Young-Sun, Cha Kyung-Joon, Oh Jae-Eung, Lee Hae-Jin, Lee Gyeong-Tae, Park Moon-Il
Department of Obstetrics and Gynecology, College of Medicine, Wonkwang University, Sanbon Medical Center, Gyeonggi, Korea.
J Perinat Med. 2007;35(3):210-6. doi: 10.1515/JPM.2007.044.
We studied how linear and nonlinear heart rate dynamics differ between normal fetuses (n=135) and uncomplicated small-for-gestational age (SGA) fetuses (n=65), aged 32-40 weeks' gestation.
We analyzed each fetal heart rate time series for 20 min. We quantified the complexity (nonlinear dynamics) of each fetal heart rate (FHR) time series by approximate entropy (ApEn) and correlation dimension (CD). The linear dynamics were analyzed by canonical correlation analysis (CCA).
The ApEn and CD of the uncomplicated SGA fetuses were significantly lower than that of the normal fetuses in all three gestational periods (32-34, 35-37, 38-40 weeks). Canonical correlation ensemble in SGA fetuses is slightly higher than normal ones in all three gestational periods, especially at 35-37 weeks.
Irregularity and complexity of the heart rate dynamics of SGA fetuses are lower than that of normal ones. Also, canonical ensemble in SGA fetuses is higher than in normal ones, suggesting that the FHR control system has multiple complex interactions. Along with the clear difference between the two groups' non-linear chaotic dynamics in FHR patterns, we clarified the hidden subtle differences in linearity (e.g., canonical ensemble). The decrease in non-linear dynamics may contribute to the increase in linear dynamics. The present statistical methodology can be readily and routinely utilized in obstetrics and gynecologic fields.
我们研究了孕龄32 - 40周的正常胎儿（n = 135）和无并发症的小于胎龄（SGA）胎儿（n = 65）的线性和非线性心率动态变化有何不同。
我们对每个胎儿心率时间序列进行了20分钟的分析。我们通过近似熵（ApEn）和关联维数（CD）对每个胎儿心率（FHR）时间序列的复杂性（非线性动力学）进行了量化。通过典型相关分析（CCA）分析线性动力学。
在所有三个孕期（32 - 34周、35 - 37周、38 - 40周），无并发症的SGA胎儿的ApEn和CD均显著低于正常胎儿。SGA胎儿的典型相关系综在所有三个孕期均略高于正常胎儿，尤其是在35 - 37周时。
SGA胎儿心率动态的不规则性和复杂性低于正常胎儿。此外，SGA胎儿的典型系综高于正常胎儿，这表明FHR控制系统存在多种复杂的相互作用。随着两组胎儿心率模式非线性混沌动力学的明显差异，我们阐明了线性方面（如典型系综）隐藏的细微差异。非线性动力学的降低可能导致线性动力学的增加。目前的统计方法可在妇产科领域方便且常规地应用。
