Divon M Y, Zimmer E Z, Platt L D, Paldi E
Am J Obstet Gynecol. 1985 Feb 1;151(3):403-6. doi: 10.1016/0002-9378(85)90312-6.
A computerized quantification of fetal heart rate and beat-to-beat variability was performed during and between fetal breathing episodes. Sixteen healthy pregnant women at term participated in the study. The results indicate that fetal breathing is associated with a significant increase in beat-to-beat variability (from 4.48 +/- 1.66 between breathing episodes to 5.80 +/- 2.04 during breathing episodes, p less than 0.01) and a small but significant decrease in fetal heart rate (from 142.7 +/- 8.6 bpm between breathing episodes to 140.4 +/- 8.6 bpm during breathing episodes, p less than 0.05).