Cardiac and venous blood flow in fetuses of insulin-dependent diabetic mothers: Evidence of abnormal hemodynamics in early gestation

OBJECTIVE: Our purpose was to determine whether in early gestation cardiac and venous blood flow patterns of fetuses of insulin-dependent diabetic mothers differ from those of normal fetuses. STUDY DESIGN: Serial recordings were obtained at 12, 16, and 20 weeks of gestation in 11 normal fetuses, 16 fetuses of insulin-dependent diabetic mothers with first-trimester glycosylated hemoglobin levels less than or equal to 8.5% (group 1), and 11 fetuses of insulin-dependent diabetic mothers with first-trimester glycosylated hemoglobin levels >8.5% (group 2). Velocity waveforms al the level of atrioventricular valves, inferior vena cava, and umbilical vein were recorded by means of color and pulsed Doppler equipment by either transvaginal or transabdominal approaches. The following variables were measured: ratio between the peak velocities during early passive ventricular filling and active atrial filling at the level of atrioventricular valves, percent reverse flow during atrial contraction in inferior vena cava, and pulsations in umbilical vein. RESULTS: In all the fetuses the ratios between early and active ventricular filling increased linearly with advancing gestation, whereas the percent reverse flow in the inferior vena cava decreased linearly. However, fetuses of diabetic mothers showed significant differences in the slope of the functions describing the development with gestation of these index values, resulting in lower values of the ratios between early and active ventricular filling at the level of both ventricular valves and higher values of percent reverse flow in inferior vena cava. These differences were more evident in group 2 fetuses of diabetic mothers, and statistically significant differences were found in the slope values compared with group 1 fetuses. In normal fetuses umbilical vein pulsations were present only in two fetuses at 12 weeks of gestation (18.18%) and were never evidenced later in gestation. A significantly higher incidence of pulsations was found at 12 weeks in fetuses of diabetic mothers (group 1, 56.25%; group 2, 81.81%) and pulsations were present until 16 weeks (group 1, 37.5%; group 2, 45.47%). CONCLUSIONS: An impaired development of cardiac and venous blood flow patterns occurs in fetuses of insulin-dependent diabetic mothers. These abnormalities are more evident in pregnancies with poorer glycemic control but still occur in the presence of stricter metabolic control.