Pillai M, James D
University Department of Obstetrics, Bristol Maternity Hospital, United Kingdom.
Obstet Gynecol. 1990 Nov;76(5 Pt 1):812-6. doi: 10.1097/00006250-199011000-00017.
Characteristics of the fetal heart rate (FHR) were studied longitudinally throughout the second and third trimesters in 43 low-risk singleton fetuses. The second trimester was characterized by an FHR pattern showing minimal differences between quiet and active intervals of fetal behavior. Few movements were accompanied by accelerations of small magnitude. Brief decelerations of variable magnitude exceeded the number of accelerations, and their frequency declined with advancing maturity. The percentage of body movements accompanied by FHR acceleration, the amplitude of these accelerations, and the rate of rise in heart rate increased with gestational age. Up to 30 weeks, the characteristics of the baseline FHR were similar in both periods of fetal rest and activity, with the baseline variability becoming significantly greater with advancing gestation. However, during quiet cycles of fetal behavior after 30 weeks, the baseline variability became progressively narrower, so that in late pregnancy different behavioral states could be determined reliably from characteristics of the baseline FHR alone.
对43例低风险单胎胎儿在妊娠中期和晚期进行了纵向研究，以观察胎儿心率（FHR）的特征。妊娠中期的FHR模式特点是，胎儿行为的安静期和活跃期之间差异极小。很少有胎动伴随着小幅度的加速。幅度可变的短暂减速超过了加速的次数，且其频率随着成熟度的增加而下降。伴随FHR加速的身体运动百分比、这些加速的幅度以及心率上升速率均随孕周增加。直至孕30周，胎儿休息和活动时的基线FHR特征相似，随着孕周增加，基线变异性显著增大。然而，在30周后的胎儿行为安静周期中，基线变异性逐渐变窄，因此在妊娠晚期，仅根据基线FHR的特征就能可靠地确定不同的行为状态。
