The change in fetal activity periods in diabetic and nondiabetic pregnancies.

Fetal active and quiet periods of behavioral activity were determined at 28 and 32 weeks' and 36 to 40 weeks' gestational age in insulin-dependent diabetic pregnancies and in normal pregnancies resulting in infants with weights appropriate for gestational age. Fetal active and quiet periods were based on observations of fetal movements and long-term fetal heart rate variability. The number of fetal active-quiet periods, the average duration of fetal quiet periods, and the average duration of fetal active periods were the three parameters evaluated. In the normal pregnancy groups, with increasing fetal gestational age from 28 to 32 weeks to 36 to 40 weeks there was an increase in the length of the active and quiet periods with fewer active-quiet cycles per hour. The fetuses of the diabetic women had findings similar to those of the normal group at 28 to 32 weeks; these findings were essentially unchanged at 36 to 40 weeks. These findings suggest delayed development of the active-quiet cycles in these diabetic pregnancies.