Effect of maternal glucose ingestion on fetal breathing and body movements in late pregnancy.

Fetal breathing movements and fetal whole body movements were observed over 2 hours in 22 normal singleton pregnancies between 34 and 38 weeks gestation using a real time ultrasonic B scan method. The proportion of time fetuses spent making breathing movements increased from 9.9 per cent to 48.3 per cent within one hour of their fasting mothers taking a 50 g glucose drink. Fetal whole body movements were not increased after maternal glucose ingestion. Arousal of the fetal central nervous system seems dependent on the level of fetal blood glucose.