The relationship between gestational weeks and fetal breathing movements in each pattern of the fetal heart rate

Fetal breathing movement (FBM) was analysed in each fetal heart rate (FHR) pattern and the gestational 2 weeks. FHR pattern was divided in automated FHR analysis into 3 groups; active, intermediate and resting patterns. The patients consisted of 102 pregnant women at 30-41 weeks, including 13 complicated pregnancies. 1) The active pattern percentage was 52.7% at 32-33 weeks and it decreased gradually. That of the resting pattern was 25.5% at 32-33 weeks and it increased gradually. 2) The percentages of positive FBM in the active pattern were significantly larger than those in the resting pattern in each 2 weeks. 3) The duration of continuous FBM ranged from 3 to 202 sec. FBM of long duration tended to exist in the resting pattern rather than in the active pattern. 4) The percent time ratio of FBM ranged from 1.0 to 92.7% and showed no definite relationship with the FHR patterns or gestational weeks. 5) The FBM rates in each FHR pattern showed no significant differences. Their sequential differences after 36 weeks were significant; that is, FBM in the resting pattern was more regular than that in the active pattern. 6) In high risk pregnancy, the resting pattern percentage was 52.3% and the ratio of positive FBM in the resting pattern was significantly smaller than that in active pattern.