Vibroacoustic stimulation and fetal hiccoughs

Hiccoughs are a physiological phenomenon, beginning in the second trimester of pregnancy, increasing in frequency throughout gestation, and continuing into the neonatal period. There is concern about the safety of the use of vibroacoustic stimulation of the third-trimester fetus as part of the evaluation of fetal well-being. This study was directed to determine whether the evoked fetal startle response would accentuate or decrease the incidence of hiccoughs. Of the 342 nonstress tests (NSTs) performed, fetal hiccoughs were heard during 39 (11.4%) tests. The incidence of hiccoughs was 10.6% (25/236) of patients stimulated with sound and 13.2% (14/106) of these without sound (P = NS). Hiccoughs were found to increase in frequency throughout the third trimester. In all nonreactive NSTs, hiccoughs were absent. This vibroacoustic stimulation did not affect the fetal physiologic response of hiccoughs, and the absence of hiccoughs in nonreactive NSTs may be another indicator of fetal compromise.