75-g oral glucose tolerance testing does not affect fetal cardiac doppler parameters in low-risk pregnant women

The study aimed to examine whether acute hyperglycemia, caused by the 75-g oral glucose tolerance test (OGTT) can produce fetal cardiac adverse effects that are detectable with fetal cardiac Doppler ultrasound in healthy low-risk pregnancies. Healthy low-risk pregnant women who underwent 75-g OGTT during the gestational period of 24 to 28 weeks were considered eligible and during the test, they were examined with fetal ultrasound at the fasting and 1- and 2-h timepoints. The study findings included the parameters of umbilical artery pulsatility index, uterine artery, fetal heart rate, middle cerebral artery (MCA) peak systolic velocity (MCA-PSV), MCA pulsatility index, and fetal cardiac Doppler parameters including myocardial performance index, left isovolumetric contraction and relaxation times, K-index, filling time, mitral E- and A-wave velocities, and E/A ratio. The data of 53 women without gestational diabetes mellitus were used for statistical analyses. There was no statistical significance among the three-time points of OGTT regarding all the Doppler parameters (p>0.05). The median MCA-PSV measured at the fasting of OGTT was significantly higher than the values measured at the first and second hour of OGTT [28 (22-42) vs. 26 (18-39) and 26 (18-38), respectively; p<0.05]. This increase provided no relationship with other study parameters (p>0.05). Overall, 75-g OGTT does not affect fetal cardiac Doppler parameters in healthy pregnant women except for abnormal findings of MCA-PSV. The results of the current study can provide significant support to clinicians in reducing the hesitations of women with low-risk pregnancies regarding gestational diabetes screening.