Discussion
Diabetes is the most common endocrine disorder during pregnancy. Fetal-maternal morbidity is significantly reduced if diabetes is diagnosed and precautions are taken. In this study, we evaluated fetal EFT, which is a candidate to be a new marker to determine maternal diabetes status in pregnancy. Unlike other studies in the literature, we took one step further by separately evaluating fetal EFT in pregnancies with both PGDM and GDM. Cut off values of EFT for the diagnosis of diabetes risk were also identified.
It is known that epicardial adipose tissue has important paracrine and metabolic effects. EFT is closely related to excess fat tissue in the body. However, the main reason for EFT to be a reliable marker is that EFT is not affected by changes in subcutaneous and muscle tissues12. Previous studies in adults revealed that increase in EFT is an important diabetic marker and may be a determinant in terms of morbidities that may occur due to diabetes22. Furthermore, a close relationship was found between EFT and metabolic syndrome, obesity and insulin resistance8.
Some recent studies investigated whether use of EFT as a marker in adults could be beneficial for pregnant women and their fetuses. In the study by Jackson et al., EFT of fetuses was compared between diabetic and non-diabetic pregnant women16. They found that fetal EFT was statistically significantly higher in diabetic pregnant women (EFT mean=1.43mm). However, in their studies, diabetic pregnancies were not grouped and evaluated as PGDM and GDM. Similarly, we found that EFT of fetuses was higher in diabetic pregnant women compared to non-diabetic pregnancies. Unlike to other studies, we also demonstrated that fetal EFT was significantly higher in pregnancies with PGDM compared to those with GDM.
In our study, we found that maternal age and values of HbA1C, AC and DVP were significantly higher in PGDM and GDM groups. Although maternal age was not significantly different between GDM and control groups, pregnant women with PGDM were significantly older than both GDM and control groups. We’ve also oberved a statistically significant correlation between fetal EFT and maternal age. Most of the previous studies did not explore any significant relationship between fetal EFT and maternal age15,17,18. Only in the study of Akkurt et al., maternal age was found to be greater in diabetic pregnant women as in our study6. The reason for higher maternal age in pregnant women with PGDM may be explained by the desire of women with existing diabetes to postpone their pregnancy to a later age. Another explanation is that these women with PGDM are more likely suffer from comorbidities which increase the risk of failure to conceive.
Since diagnosis of PGDM was established at the first trimester of pregnancy in our study population, OGTT was performed to GDM and control groups. We found that fetal EFT was significantly positively correlated with every parameter of OGTT values (fasting, 1st hour and 2nd hour). Although this correlation was weak for FPG level, it was strong for 1st hour and 2nd hour glucose levels after OGTT. Similarly, Yavuz et al. compared and correlated fetal EFT values and blood glucose measurements obtained during a 75-gr OGTT18. In their study, fetal EFT had a significantly weak and moderate correlation with 1st hour and 2nd hour glucose level after controlling for maternal age, gestational age, body mass index and abdominal circumference. However, when only GDM pregnancies were included, fetal EFT was positively and moderately related to 2-h glucose values18. Furthermore, we also explored that there was a significant and moderate positive correlation between fetal EFT values and maternal HbA1c levels. Confirming our results, Aydin et al. observed a strong positive correlation between fetal EFT and maternal HbA1C values17. In this study, fetal EFT was found to be significantly associated with adverse perinatal outcomes of diabetes including macrosomia and polyhydramnios. Fetal EFT was significantly positively correlated with fetal AC and DVP of amniotic fluid volume. Akkurt et al. were also demonstrated a higher fetal EFT in pregnancies with GDM compared to normal pregnancies6. Unlike from our study, Aydin et al. were determined a positive correlation between fetal EFT and DVP values instead of AC values17. However, they compared fetal EFT values only between GDM and control groups. Among all three groups in our study, HbA1c, AC and DVP values were significantly higher in PGDM group followed by GDM group. These findings provide strong evidence that high EFT value is a fetal reflection of poorly controlled maternal glucose level.
In this study, we investigated the diagnostic value of fetal EFT on diabetic pregnancies and determined cut-off EFT values for both PGDM and GDM. Until recently, there are two studies in the literature that calculate which values of fetal EFT can be used as cut-offs for diabetes in pregnancy. The first of these was done by Akkurt et al. in 20186. The recommended equation of the mentioned study for calculation of EFT in pregnant women with diabetes was EFT = 0.05 x gestational age + 0.07 (R2 = 0.70). In our study, we did not calculate the equation related to the gestational week. Instead, we evaluated EFT of all pregnant women in the same week to ensure standardization. Another study in the literature was performed by Aydin et al. in 202015. They conducted a study to determine the relationship between fetal EFT and weight. Aydin et al. stated that a cut-off fetal EFT value above 1.38 mm was predictive for diagnosis of fetuses with large for gestational age with a sensitivity of 94.4% and a specificity of 97.6%15. All patients in that study were evaluated at 22 weeks of gestation, but diabetic pregnancies were not grouped as PGDM and GDM. In the present study, cut-off EFT values for pregnant women with PGDM and GDM were 1.30 mm (sensitivity 97.3%, specificity 98.2%) and 1.27 mm (sensitivity 94%, specificity 95%), respectively. Both EFT cut-off values of our study were found to be lower than the values calculated by Aydin et al. and Akkurt et al.6,17 We believed that the reason for this difference is related to patient selection criteria and classification of study population rather than measurement technique of fetal EFT.