FETAL CATECHOLAMINE RESPONSES TO VIBROACOUSTIC STIMULATION

OBJECTIVE: The aim of this study was to determine whether fetal vibroa coustic stimulation caused a surge of catecholamines from the fetal sy mpathoadrenal system. STUDY DESIGN: A randomized, prospective, control led trial was performed at The Queen Mother's Hospital, Glasgow. Circu lating catecholamine levels in cord blood from a group of fetuses who received vibroacoustic stimulation 1 to 2 minutes before delivery by e lective cesarean section (n = 25) were compared with those from a grou p of controls (n = 23) (Mann-Whitney U test). Fetal heart rate respons e to vibroacoustic stimulation was recorded in 10 additional pregnanci es under identical experimental conditions. RESULTS: No differences we re found in norepinephrine or epinephrine levels between the vibroacou stic stimulation group and the control group. A positive fetal heart r ate response was observed in seven of 10 fetuses tested. Fetal norepin ephrine levels were also found to be influenced by maternal blood pres sure and administration of ephedrine. CONCLUSIONS: Under these conditi ons vibroacoustic stimulation does evoke the characteristic fetal hear t rate response, but it does not induce a surge of catecholamines from the fetal sympathoadrenal system. Therefore it is unlikely that the i mmediate fetal heart rate response to vibroacoustic stimulation is ind uced by a surge in systemic catecholamines.