Umbilical artery blood flow velocity waveforms in pregnancy complicated by diabetes mellitus.

Umbilical artery blood velocity waveforms were recorded by a pulsed Doppler system in the third trimester of pregnancy in 16 diabetic women (12 class B, 1 class C, 3 class D) and the waveforms were analysed for resistance index (RI = peak systolic velocity minus end diastolic velocity/peak systolic velocity). There was no significant correlation between the RI values and either serum glucose (r = 0.385) or fructosamine levels (r = 0.380). However, the RI values were raised in two cases with serum glucose levels of over 300 mg/dl. With a fall in serum glucose levels, the RI values returned to the normal range. No abnormal umbilical artery velocity waveforms were found when the serum glucose level was below 200 mg/dl.