Use of sound-elicited fetal heart rate accelerations to assess fetal hearing in the second and third trimester.
Level 4 - case-series / case-control
Observational cross-sectional study evaluating physiological response across gestational ages without a separate control group.
PubMed 32222580 · doi:10.1016/j.ijporl.2020.110001
What was done
Fetuses between 20 and 37 weeks of gestational age received transabdominal sound stimulation with a 2000 Hz pure tone at 90 dB for 5 seconds. Fetal heart rate changes before and after sound exposure were monitored using a cardiotocometer to evaluate the optimal gestational window and baseline heart rate conditions for detecting sound-evoked responses.
What was found
The rate of positive fetal heart rate accelerations increased significantly at 26–27, 28–29, 30–31, and 34–35 weeks compared to the rate at 20–21 weeks of gestation (exact percentages and p-values not reported in abstract). Baseline fetal heart rate variability (minimal vs. moderate) did not affect response rates between 20 and 27 weeks. Between 28 and 37 weeks of gestation, the detection rate of sound-elicited accelerations reached 100% when testing occurred during moderate baseline fetal heart rate variability.
Why it matters
These findings define the gestational timing (28–37 weeks) and physiological state (moderate baseline variability, indicating active sleep) required to elicit reliable fetal cardiac responses to acoustic stimuli, supporting potential protocols for prenatal auditory evaluation.
Limits
The abstract does not report the total sample size, participant selection criteria, or exact numerical values for comparisons (such as baseline response rates or p-values). Postnatal hearing outcomes were not evaluated to validate diagnostic performance.
Cited by
- supports Human auditory perception begins during the second trimester of fetal development in utero.