Maturation of fetal heart rate and body movement in 24-33-week-old fetuses threatening to deliver prematurely

Maturation of spontaneous cardiac and body movement behavior from 24 to 33 weeks gestational age was characterized prospectively in 168 high-risk fetuses threatening to deliver prematurely. Forty-eight, low-risk fetuses delivering as healthy full-term infants served as a comparison group. Fetuses were classified on the basis of gestational age at time of testing and newborn outcome following delivery (high-risk: premature compromised, premature healthy, term healthy infant; low-risk term healthy). In the high-risk group, the average fetal heart rate was greater and decreased over gestation from 148 to 140 bpm, regardless of outcome. In the low-risk group, it decreased from 145 to 138 bpm. In high- and low-risk groups, the average number of heart rate accelerations greater than or = 15 bpm increased over gestation from 2-3 to 8 while the average number of maternally perceived movements decreased. It was concluded that maturational changes in spontaneous fetal heart rate and maternally perceived body movements in fetuses threatening to deliver prematurely parallel those of low-risk fetuses.