Differential maturation of fetal responses to vibroacoustic stimulation in a high risk population

Abstract

Maturation of human fetal response to vibroacoustic stimulation was examined in 163 high risk fetuses from 23 to 36 weeks gestational age (GA). Each fetus received three vibroacoustic trials and three no‐stimulus control trials (randomly assigned) while fetal heart rate (FHR) was recorded and body movement was observed on ultrasound scan. For data analyses, fetuses were categorized into preterm compromised (n = 57), preterm healthy (n = 42) and term healthy (n = 64) based on evidence of compromise at birth. Differential maturation was observed among the outcome groups. The term healthy group exhibited a body movement and, on the first stimulus trial, an FHR deceleration response at 27 weeks GA with a shift to an FHR acceleration response at 30 weeks GA. By 33 weeks GA, responding was indistinguishable from that reported for low risk fetuses with response rates of 92% for both movements and FHR accelerations. The preterm healthy outcome group showed a body movement and an FHR acceleration response at 27 weeks GA. Over gestation, there was no maturation of either response. The preterm compromised outcome group showed a body movement response at 24 weeks GA which did not mature. An FHR acceleration response was elicited at 27 weeks GA with the magnitude of the acceleration increasing over gestation; at 33 weeks GA the magnitude was below that observed in the term healthy group. With advancing gestation, the rate of cardiac–movement coupling increased only in the two healthy outcome groups. It was concluded that differential fetal behaviour as a function of fetal/newborn outcome may reflect differential functional development of the fetal nervous system.