Fetal breathing movements in late diabetic pregnancy: relationship to fetal heart rate patterns and Braxton Hicks' contractions.

In type-1 diabetic pregnancy, the occurrence of fetal breathing movements (FBM) was studied in relation to the fetal heart rate patterns (HRPs) A and B and to Braxton Hicks' contractions. Simultaneous 2-h recordings of fetal heart rate and body, eye and breathing movements were available for analysis (n = 44). These recordings were made in 20 fetuses of diabetic women at 32-38 weeks of gestation. Uterine activity was monitored at 36 and 38 weeks. For all recordings combined, the median incidences of FBM during HRPs A and B were 23% and 41%, respectively (NS). At low overall breathing activity (< 50% of total observation time), FBM were more numerous during HRP B than during HRP A in 83% of the recordings. However, if the overall breathing activity exceeded 50% of time FBM were preferentially made during HRP A in 93% of the recordings. This relationship was most pronounced at 38 weeks. These results corroborate our previous findings in the healthy near-term fetus. They show even more clearly that the state-dependent occurrence of FBM depends on the fetus' drive to breathe. During the recordings, breathing activity remained unchanged at all gestational ages studied, in contrast to the gradual decline in FBM seen in normal pregnancy. Braxton Hicks's contractions had no effect on FBM, which differs from the specific distribution of FBM during uterine contractions as previously found in uncomplicated pregnancies. We conclude that FBM in late diabetic pregnancy are not influenced by Braxton Hicks' contractions and that they do not show a clear-cut state-dependency. The (neural) mechanism underlying FBM differs from that in normal pregnancy.