Human umbilical and fetal cerebral blood flow velocity waveforms following maternal glucose loading: a...

Our aim was to study umbilical and fetal cerebral arterial blood flow velocity waveforms related to fetal biometric measures and maternal body mass index, glucose levels and parity following maternal oral glucose loading.

The study had an experimental design in a cross-sectional observational study including 105 low-risk pregnancies (30-32 weeks of gestation). Ultrasound Doppler measurements of umbilical and middle cerebral arterial (UA and MCA) velocity waveforms were performed before and at 2 h after completed 75-g oral glucose tolerance tests (OGTT). We assessed changes in UA and MCA pulsatility indices (PI).

MCA PI was significantly reduced following OGTT (p < 0.001); these changes were not related to changes in fetal heart rate (r = -0.11, p = 0.278). UA PI was also significantly reduced following OGTT (p = 0.033); these changes were related to fetal heart rate (r = -0.47, p < 0.001). This reduction was not significant (p = 0.230) when the PI values were adjusted for fetal heart rate. The ratio MCA PI to UA PI was reduced (p = 0.001). The effect of OGTT on MCA PI was not related to fetal abdominal circumference whereas the effect on the adjusted UA PI values was correlated to abdominal circumference (r = -0.20, p = 0.045) but not to abdominal circumference Z-score (r = -0.16, p = 0.115). The influence of OGTT on the Doppler parameters as well as heart rates was not related to prepregnant body mass index, glucose levels before or after OGTT, parity, fetal sex or gestational age.

Maternal glucose loading seems to decrease fetal cerebral blood flow impedance independent of fetal size.