The relationship between hiccups and heart rate in the fetus

Objective. The purpose of this study was to determine the effect of fetal hiccups on fetal heart rate from 20 weeks of gestation onward. Methods. One thousand four hundred and fifty-six collected fetal heart rate tracings from three cohorts that participated in longitudinal studies of fetal neurobehavioral development were reviewed retrospectively for fetal hiccups. Tracings were recorded at four-week intervals from 20 weeks. A hiccup-free period before or after the episode of hiccups was used as the control fetal heart rate; thus each fetus was used as its own control. The paired t-test was used for statistical analysis. Results. From 28 weeks onward, the mean fetal heart rate increased with hiccups reaching statistical significance at 32 weeks. Fetal heart rate variability was unaffected by hiccups until 36 weeks, at which time it decreased during hiccup periods. Conclusion. This change in response to fetal hiccups may represent another neurodevelopment milestone for the fetus.