The effect of glucose on Doppler flow velocity waveforms and heart rate pattern in the human fetus

The effect of 50 GR oral glucose tolerance test on fetal celiac artery and superior mesenteric artery Doppler parameters in healthy pregnancies

OBJECTIVES

To understand the effect of 50-g oral glucose tolerance test (OGTT) on fetal celiac artery and superior mesenteric artery (SMA) Doppler parameters.

METHODS

A total of 43 healthy pregnant women followed in our hospital were included in the study. All Doppler parameters of the celiac artery and SMA (peak systolic velocity (PSV); pulsatility index (PI); resistance index (RI); systolic/diastolic ratio (SD); time average maximum velocity (TAMAX)) were obtained by ultrasonography before and 1 h after OGTT.

RESULTS

The mean PSV value of the celiac artery decreased statistically significantly after OGTT (37.29 ± 11.96 cm/s; 29.51 ± 10.07 cm/s; p=0.002). While the mean of the PI was 2.09 ± 0.57 before the test, it was found to be 1.84 ± 0.64 after the test (p=0.027). Mean PSV (39.82 ± 13.07 cm/s; 35.19 ± 15.27 cm/s; p=0.104) and PI (2.21 ± 0.65; 2.11 ± 0.80; p=0.375) values of SMA were also found to be decreased without statistically significancy.

CONCLUSIONS

The data obtained from our study reveals that the PSV and PI values of celiac artery and SMA slightly decrease after OGTT.

Effect of a standardized maternal meal on fetal middle cerebral artery Doppler indices: A single-blinded crossover study

Objective

Measures of Doppler blood flow velocity profiles are an integral part of monitoring fetal well-being during pregnancy. These examinations are performed at different times of the day and at different maternal meal states. In uncomplicated pregnancies, we assessed the effect of a standardized maternal meal on middle cerebral artery (MCA) and umbilical artery (UA) Doppler blood flow velocity pulsatility indices (PIs) and MCA peak systolic velocity (PSV).

Methods

In this prospective single-blinded crossover study 25 healthy women were examined at 36 weeks of pregnancy. The first examination was performed in the morning following overnight fast, and repeated after extended fast (state A), and after a standard breakfast meal (state B).

Results

Irrespective of maternal prandial status, the MCA-PI values were lower in the 2^nd compared to the 1^st examination (-0.187; p = 0.071, and -0.113; p = 0.099, state A and B, respectively). Compared to the values in the 1^st examination, the UA-PI values, were higher after extended fast (0.014; p = 0.436), and lower post-prandially (-0.036; p = 0.070). The difference (state B minus state A) between the meal states were not significant (0.074; p = 0.487 and -0.050; p = 0.058, for MCA-PI and UA-PI, respectively). Adjusting for the possible influence of fetal heart rate on MCA-PI and UA-PI, the differences between meal states remained non-significant (p = 0.179, p = 0.064, respectively). The MCA-PSV values increased after the meal (6.812; p = 0.035), whereas no increase was observed following extended fast (0.140; p = 0.951). The difference in MCA-PSV values between the two meal states was not significant (6.672; p = 0.055).

Conclusion

Our results demonstrate possible diurnal variations in MCA-PI and UA-PI, with and without adjustment for fetal heart rate, that seem to be unaffected by maternal meal intake in healthy pregnancies.

The effect of glucose tolerance test on fetoplacental circulation

OBJECTIVE

Acute hyperglycemia affects the fetoplacental circulation. This study aims to investigate the possible effect of acute hyperglycemia induced by 50 g oral glucose tolerance test (OGTT) on fetoplacental circulation in women between 24 and 28 weeks of gestation.

MATERIALS AND METHODS

Between January 2019 and April 2019, a total of 29 women who were between 24 and 28 weeks of gestation with a singleton gestation and were in low-risk group were included in this prospective study. All patients underwent fetal biometric measurements using ultrasonography (USG) and were administered 50 g OGTT. Before and 1 h after the test, Doppler USG was used to measure uterine artery, umbilical artery (UA), middle cerebral artery (MCA), pulsatility index (PI), resistance index (RI), and systolic/diastolic (S/D) ratio. The cerebroplacental ratio (CPR) was calculated as the ratio of the MCA-PI/UA-PI.

RESULTS

There was a decline in the MCA-RI (p = 0.008) and UA-PI (p = 0.021) at 1 h after the administration of 50 g OGTT. Z-scores of the mean UA-PI, MCA-PI, and CPR were calculated and a statistically significant increase in the Z-scores of the mean UA-PI was observed (p = 0.028).

CONCLUSION

Our study results show that acute hyperglycemia induced by OGTT significantly increases the Z-scores of the UA-PI, affecting the fetoplacental circulation.

The effect of 75-g oral glucose tolerance test on maternal and foetal Doppler parameters in healthy pregnancies: a cross-sectional observational study

Hyperglycaemia can alter placental resistance to blood flow and hyperglycaemia has adverse perinatal outcomes. Oral glucose tolerance testing (OGTT) increases the maternal plasma glucose levels temporarily and mimics metabolic hyperglycaemia. The blood flow of the uterine artery (UtA), umbilical artery (UA), middle cerebral artery (MCA) were assessed before, 1 and 2 h following the OGTT by using Doppler ultrasonography. Z-score of cerebroplacental ratio (CPR), pulsatility index (PI) for three vessels were evaluated separately. All measurements of the MCA, UA, UtA Doppler parameters were not statistically different for fasting, and 1 and 2 h following the 75 g OGTT in the 53 pregnant women with a singleton gestation in the low-risk group. This study results show that acute hyperglycaemia induced by OGTT has no effect on maternal and foetal Doppler parameters in healthy pregnancies.IMPACT STATEMENTWhat is already known on this subject? Foetal glucose is affected by maternal blood glucose concentrations and placental blood flow. Acute hyperglycaemia may have an effect on maternal, and foetal Doppler parameters among healthy pregnanciesWhat do the results of this study add? Our findings indicate that blood flow velocity metric measurements in the UA, MCA and UtA were not affected by the OGTT in healthy pregnant women.What are the implications of these findings for clinical practice and/or further research? Acute hyperglycaemia induced by OGTT does not have any effect on fetomaternal circulation, especially foetal brain blood flow. Other foetal vessels including ductus venosus, renal artery, etc. may be affected by maternal blood glucose levels during the OGTT or in diabetic patients. Future prospective studies consisting of diabetic patients are warranted to verify the exact effect of glucose levels on foetal and maternal circulation.

A maternal meal affects clinical Doppler parameters in the fetal middle cerebral artery

INTRODUCTION

Middle cerebral artery (MCA) and umbilical artery (UA) Doppler blood flow pulsatility indices (PIs) and MCA peak systolic velocity (PSV) are essential variables for clinically evaluating fetal well-being. Here we examined how a maternal meal influenced these Doppler blood flow velocity variables.

METHODS

This prospective cohort study included 89 healthy Caucasian women with normal singleton pregnancies (median age, 32 years). Measurements were performed at gestational weeks 30 and 36, representing the start and near the end of the energy-depositing period. Measured variables included the MCA-PI, UA-PI, fetal heart rate (FHR) and MCA-PSV. The cerebroplacental ratio (CPR) was calculated as the ratio of MCA-PI to UA-PI. The first examination was performed in the fasting state at 08:30 a.m. Then participants ate a standard breakfast (approximate caloric intake, 400kcal), and the examination was repeated ~105 min after the meal.

RESULTS

Without adjustment for FHR, fetal MCA-PI decreased after the meal at week 30 (‒0.115; p = 0.012) and week 36 (‒0.255; p < 0.001). All PI values were negatively correlated with FHR. After adjustment for FHR, MCA-PI still decreased after the meal at week 30 (‒0.087; p = 0.044) and week 36 (‒0.194; p < 0.001). The difference between the two gestational weeks was non-significant (p = 0.075). UA-PI values did not significantly change at week 30 (p = 0.253) or week 36 (p = 0.920). CPR revealed significant postprandial decreases of -0.17 at week 30 (p = 0.006) and -0.22 at week 36 (p = 0.001). Compared to fasting values, MCA-PSV was significantly higher after food intake: +3.9 cm/s at week 30 (p < 0.001) and +5.9 cm/s at week 36 (p < 0.001).

CONCLUSION

In gestational weeks 30 and 36, we observed a postprandial influence that was apparently specific to fetal cerebral blood flow.

Gestational diabetes alters the fetal heart rate variability during an oral glucose tolerance test: a fetal magnetocardiography study

OBJECTIVE

Gestational diabetes mellitus (GDM) potentially harms the child before birth. We previously found GDM to be associated with developmental changes in the central nervous system. We now hypothesise that GDM may also impact on the fetal autonomic nervous system under metabolic stress like an oral glucose tolerance test (OGTT).

DESIGN

We measured heart rate variability (HRV) of mothers and fetuses during a three-point OGTT using fetal magnetocardiography (fMCG).

SETTING

Measurements were performed in the fMEG Centre in Tübingen.

POPULATION

After exclusion of 23 participants, 13 pregnant women with GDM and 36 pregnant women with normal glucose tolerance were examined.

METHODS

All women underwent the same examination setting with OGTT during which fMCG was recorded three times.

MAIN OUTCOME MEASURE(S)

Parameters of heart rate variability were measured.

RESULTS

Compared with mothers with normal glucose regulation, mothers with GDM showed increased heart rate but no significant differences of maternal HRV. In contrast, HRV in fetuses of mothers with GDM differed from those in the metabolically healthy group regarding standard deviation normal to normal beat (SDNN) (P = 0.012), low-frequency band (P = 0.008) and high-frequency band (P = 0.031). These HRV parameters exhibit a decrease only in GDM fetuses during the second hour of the OGTT.

CONCLUSIONS

These results show an altered response of the fetal autonomic nervous system to metabolic stress in GDM-complicated pregnancies. Hence, disturbances in maternal glucose metabolism might not only impact on the central nervous system of the fetus but may also affect the fetal autonomic nervous system.

TWEETABLE ABSTRACT

Metabolic stress reveals a different response of fetal autonomic nervous system in GDM-complicated pregnancies.

Effect of short-term maternal fasting in the third trimester on uterine, umbilical, and fetal middle cerebral artery Doppler indices

OBJECTIVE

To assess the effect of short-term maternal fasting on uterine, umbilical, and middle cerebral artery Doppler indices, and on maternal serum glucose levels and fetal behavior.

METHODS

Maternal serum glucose levels, fetal biophysical profiles, and uterine, umbilical, and middle cerebral artery Doppler indices were assessed in 110 healthy women in the third trimester of pregnancy after fasting for 10-12 hours and 2 hours after a balanced meal.

RESULTS

Maternal serum glucose levels, nonstress test results, fetal breathing movements, and biophysical profile improved after a meal compared with after fasting for 10-12 hours. Uterine, umbilical, and middle cerebral artery Doppler indices were not significantly different after fasting and after a meal.

CONCLUSION

Short-term maternal fasting during the third trimester of pregnancy has no effect on uterine, umbilical, or fetal cerebral artery Doppler indices, and has a transient but significant effect on maternal serum glucose levels and fetal behavior.

The effect of intermittent maternal fasting on computerized fetal heart tracing

OBJECTIVE

To determine effects of maternal fasting on antepartum computerized fetal heart tracing analysis.

STUDY DESIGN

This was a cross-sectional study of two groups of healthy pregnant women who were recruited, a fasting and a nonfasting control group. Each pregnant woman gave a blood sample, and had a computerized fetal heart tracing.

RESULTS

A total of 124 pregnant women were studied. The mean hours since the last oral intake were significantly different between the two groups (p=0.003). Fetuses of fasted mothers had fewer episodes of large acceleration compared to the controls (p=0.001). This difference was significantly associated with maternal appreciation of fetal movement (p=0.003).

CONCLUSION

The number of large accelerations in computerized fetal heart tracing is decreased in pregnant women abstaining from food and water.

Computerized analysis of fetal heart rate after maternal glucose ingestion in normal pregnancy

OBJECTIVE

To examine the effect of maternal oral glucose ingestion on antepartum FHR indices in normal pregnancies at term.

STUDY DESIGN

A prospective study was performed on 44 non-laboring healthy women with normal singleton pregnancy at 37-40 weeks gestation. All women had a normal oral glucose tolerance test at 24-28 weeks gestation. FHR was recorded with the Sonicaid Fetal Monitor System (Oxford 8000), for 30 min prior to and 60 min following oral ingestion of 50 g of glucose in the study group of 27 women, and following water ingestion in a control group of 17 women.

RESULTS

All pregnancies had a normal outcome. The maternal blood glucose levels before and 30 and 60 min after glucose ingestion were 70+/-14, 107+/-121, and 106+/-22 mg/dl, respectively (P<0.001). A significant negative correlation was found between the changes in maternal blood glucose levels 30 min after glucose ingestion and the changes in the number of large FHR accelerations at 30 and 60 min after glucose ingestion (r=-0.44, P<0.01 and r=-0.42, P<0.01, respectively). A significant correlation was found between the changes in maternal blood glucose levels 30 min after glucose ingestion and changes in episodes of low FHR variation at this time period (r=0.45, P<0.01). No significant changes in any of the FHR variables were noted in the control group.

CONCLUSION

In normal pregnancies FHR indices of variation tend to decrease after maternal oral ingestion of glucose.

Fetal middle-cerebral and umbilical artery flow assessments after glucose challenge test

OBJECTIVE

To determine whether a change occurs in fetal middle-cerebral and umbilical artery flow after glucose challenge testing.

METHOD

Fetal middle-cerebral and umbilical artery flow was assessed by Color Dopppler technology in 21 pregnant patients before and after the 50-g glucose challenge test. The resistance index (IR) was evaluated separately for each vessel. Statistical significance was determined by Chi-square test and repeated measurement analysis with two co-variates.

RESULTS

After glucose ingestion the RI was significantly decreased in the middle-cerebral artery, but not in the umbilical artery. A significant increase in RI was recorded in the umbilical artery when maternal plasma glucose level exceeded 102 mg%.

CONCLUSION

Maternal ingestion of glucose significantly alters blood flow velocimetry in the fetal middle-cerebral and umbilical arteries. These changes may lead to the misinterpretation of normal results. It is therefore recommended that sonographic flow velocimetry assessment not be performed early after concentrated glucose ingestion.