Fetal cyclic motor activity in diabetic pregnancies: sensitivity to maternal blood glucose.

Spontaneous fetal movement in the last third of human gestation is dominated by irregular oscillations on a scale of minutes (cyclic motility, CM). The core properties of these oscillations are stable during the third trimester of gestation in normal fetuses, but disrupted by poorly controlled maternal diabetes. Here we investigated whether fetal CM is linked to short-term instabilities in maternal glucose metabolism. The fetuses of 40 mothers with type I (n = 28) or gestational (n = 12) diabetes were studied one to six times between 27 and 40 postmenstrual weeks of gestation. Fetal movement and maternal blood glucose concentration were measured during two separate periods of fetal activity in each session. Fetal CM was quantified with spectral analysis. Early in the third trimester, changes in the rate of oscillation in fetal CM between the two periods of activity were inversely related to changes in maternal blood glucose levels. Fetal CM was unrelated to concurrent maternal blood glucose levels at any point in the third trimester. The pattern of results suggests that disruption of the temporal organization of spontaneous fetal motor activity in pregnancies complicated by maternal diabetes represents an acute response to fluctuations in the metabolic environment rather than an alteration of CM development.