Effects of human maternal venous plasma glucose concentrations on fetal breathing movements.

Human fetal breathing movements were studied following the maternal ingestion of either a 50 Gm. oral glucose load or an equal volume of water in 22 healthy women with uncomplicated pregnancies at 32 to 34 weeks' gestation. The percentage of time spent breathing in fetuses of glucose-treated mothers increased from 23.2 +/- 2.2 per cent during the control period to a maximum of 58.9 +/- 5.2 per cent at 105 minutes following the oral glucose load (p less than 0.01) which was one hour following the peak maternal plasma glucose concentration. No similar increase in maternal glucose concentrations or percentage time spent breathing occurred in patients receiving water. Fetal breathing movements were observed in 97 per cent of the 15 minute periods during the second and third hour after maternal ingestion of a 50 Gm. oral glucose load. It was concluded that maternal carbohydrate intake two hours prior to fetal breathing observations should be documented to permit adequate interpretation of fetal breathing activity.