Relationship between the Duration of Fetal Breathing Movements and Gestational Age and the Development ofthe Central Nervous System at 25–32 Weeks of Gestation in Normal Pregnancy

Abstract

In 15 pregnant women with normal pregnancy at 25-32 weeks of gestation, fetal breathing movements (FBM), fetal body movements and fetal heart rate were continuously and simultaneously recorded over a total period of 180 min. The frequency of successive FBM with a duration less than 10 s (apnea period greater than 3 s) showed a significant decrease (p less than 0.01), while the frequency of successive FBM with a duration greater than or equal to 30 s showed a significant increase from 25 to 32 weeks of gestation (p less than 0.001). Strong positive correlations were also demonstrated between the frequency of FBM with a duration of greater than or equal to 30 s and the number of fetal heart rate accelerations per hour, acceleration/fetal body movement ratio, and the value of fetal heart rate long-term variability. These results suggest that the length of the duration of successive FBM represents a useful parameter for the analysis of fetal respiratory patterns, and that a prolongation of the duration of successive FBM of an individual fetus is related to the functional development of the central nervous system.