[Human fetal breathing movements: basic analysis and clinical relationship to fetal well-being (author's transl)]

By means of real time B-scan, human fetal breathing movements (FBM) was basically and clinically investigated on 244 observations in 215 pregnancies. The results obtained were as follows. (1) FBM was frequently observed during active sleep in which FHR variability and fetal movement increased. (2) The incidence of FBM increased rapidly from 12.5% at 23-27 weeks to 77-100% at more than 35 weeks gestation, but reduced to 44% at delivery. (3) FBM became more regular and deeper with advancing weeks of pregnancy, especially after 36 weeks of gestation. The frequency of FBM in normal pregnancy was slightly high at 28-29 weeks, but almost the same rates at 30-41 weeks. (4) Maternal mean blood glucose level of 6 cases (72.3 +/- 5.8 mg/dl) in which FBM absent in repeated observations was significantly lower than those of 10 cases (94.7 +/- 14 mg/dl) in which the percentage time spent breathing were 50% or more. (5) Clinically, a relationship between the presence or absence of FBM and Apgar score was not recognized. However, when the percentage time spent breathing was less than 30% or FBM was continuous and considerably deep, the incidence of neonatal asphyxia or FHR abnormality during labor was significantly increased.