Use of sound-elicited fetal heart rate accelerations to assess fetal hearing in the second and third trimester.

OBJECTIVES: We previously reported that fetal heart rate (FHR) accelerations could be obtained after fetal sound stimulation. We examined FHR accelerations during 20-37 weeks gestational age (GA) in order to assess the optimal time for the test. METHODS: The fetus was stimulated from the maternal abdomen with pure tone 2000 Hz, 90 dB, 5 s. Changes in the FHR before and after the sound stimulation were measured by a cardiotocometer. RESULTS: Compared with the positive rate of FHR accelerations at 20-21 weeks GA, significant increases were recognized in 26-27, 28 to 29, 30 to 31, and 34-35 weeks GA. Comparing the positive rate of FHR accelerations between the minimal and moderate variability of FHR baseline, no significant differences were observed at 20-27 weeks GA. On the other hand, at 28-37 weeks GA, the positive rate to detect FHR accelerations due to sound stimulation was 100% in moderate FHR baseline variability. CONCLUSION: Considering development of human fetal hearing, the method should be performed between 28 and 37 weeks GA and during moderate FHR variability corresponding to active sleep conditions. The method developed in the present study may provide a promising tool for evaluating the fetal hearing.

Deficient maternal zinc intake-but not folate-is associated with lower fetal heart rate variability.

OBJECTIVE: Few studies of maternal prenatal diet and child development examine micronutrient status in relation to fetal assessment. METHODS: Twenty-four-hour dietary recall of zinc and folate and 20min of fetal heart rate were collected from 3rd trimester pregnant adolescents. RESULTS: Deficient zinc was associated with less fetal heart rate variability. Deficient folate had no associations with HRV. Neither deficient zinc nor deficient folate was related to fetal heart rate. CONCLUSIONS: These findings, from naturalistic observation, are consistent with emerging data on prenatal zinc supplementation using a randomized control design. PRACTICAL IMPLICATION: Taken together, the findings suggest that maternal prenatal zinc intake is an important and novel factor for understanding child ANS development.