Blood flow velocity waveforms of the fetal middle cerebral artery in pregnancies complicated by diabetes mellitus.

Fetal blood flow velocity waveforms of the middle cerebral artery were measured by pulsed Doppler ultrasound in 43 pregnant women with diabetes mellitus (33 class B, 3 class C, 6 class D and 1 class R). The recordings were performed between 24 and 38 weeks of gestation. A total of 122 recordings were analyzed prior to establishing the resistance index (RI = peak systolic velocity minus diastolic velocity/peak systolic velocity). The mean maternal serum glucose was 124.3 mg/dl (range: 72.7 to 281.5 mg/dl), the mean hemoglobin A1c was 6.03% (range: 3.3 to 11.0%) and the mean fructosamine level was 255.97 mumol/L (range: 205 to 397 mumol/L). The resistance index did not differ between the fetuses of the diabetic mothers in our study population. Additionally, no significant correlation was noted between RI values and serum glucose levels (r = 0.03), hemoglobin A1c levels (r = 0.13) or fructosamine levels (r = 0.04) during the period of 26 to 34 gestational weeks. These data indicate that the RI within the fetal cerebral artery is unaffected by the maternal glycemic control when mean serum glucose levels are below 280 mg/dl.