The blood flow velocity waveform in the fetal descending aorta; its relationship to fetal heart rate pattern, eye and body movements in normal pregnancy at 27–28 weeks of gestation

Abstract

In 13 normal pregnancies at 27–28 weeks of gestation the blood flow velocity waveform at the lower thoracic level of the fetal descending aorta was studied in relation to fetal heart rate pattern (FHRP), fetal eye movements (FEM) and fetal body movements (FBM). State parameter combinations in which high fetal heart rate (FHR) variability was present, were associated with a significant reduction in pulsatility index (PI) as compared with periods in which low FHR variability was present, irrespective of FEM and FBM, indicating a reduced peripheral vascular resistance. At 27–28 weeks of gestation FHR variability and PI might be linked to baroreceptor sensitivity. PI values derived from combinations FHRP-A, FEM(—), FBM(-) and FHRP-B, FEM(+), FBM(+) showed a significant inverse relationship (P < 0.05) with FHR. FHR and FHR variability should be taken into account when studying flow velocity waveforms in the fetal descending aorta at 27–28 weeks of gestation.