Methods
The study was planned as a prospective cohort and performed among patients who applied to the Perinatology Department of Izmir Tepecik Training and Research Hospital between November 2020 and September 2022. A detailed consent form was obtained from all pregnant women participating in the study. The study was carried out in accordance with the conditions specified in the Declaration of Helsinki.
The aim of our study was to evaluate and compare the effects of maternal PGDM and GDM on EFT by ultrasonography. Therefore, we needed a group with PGDM, a group with GDM and a control group (without PGDM or GDM) to compare measurements in fetuses of the same gestational age. After the identification of patients with PGDM at first trimester of pregnancy, we performed GDM screening in order to determine the GDM and control groups. All patients without a previous diagnosis of PGDM underwent 75-gr OGTT between 26 and 28 weeks of gestation. In order to compare EFT measurements at the same gestational week for standardization, all EFT measurements were performed at 29 weeks of gestation in all pregnant women who participated in the study. Gestational week was confirmed both according to the last menstrual period and first trimester ultrasound. 161 patients with PGDM, 171 patients with GDM and 170 patients as a control group were included in the study. Pregnant women with at least one high blood glucose level in the 75-gr OGTT and with no diagnosis of previous diabetes were considered as GDM (FPG ≥ 92 mg/dl, 1st hour glucose ≥ 180 mg/dl, 2ndhour glucose ≥ 153 mg/dl). OGTT was not performed to pregnant women with PGDM. Multiple pregnancies, pregnant women with chromosomal and structural anomalies, insufficient EFT measurements (inability to obtain a clear measurement due to severe maternal obesity, unsuitable fetal position, etc.) and comorbidities accompanying pregnancy (preeclampsia, intrauterine growth retardation, metabolic disorders, etc.) were not included in the study. A flow chart of our study population was shown in Figure 1. HbA1c was measured at the 29th weeks of gestation by high-performance liquid chromatography method supplied by the Bio-Rad Diagnostic Group (Hercules, CA, USA). The treatment of GDM began with lifestyle interventions including nutritional counseling, dietary changes, and daily exercise. Fasting and postprandial self-monitoring of blood glucose were recommended in pregnancies with GDM to achieve optimal glucose levels. Glucose targets were FPG <95 mg/dL and either 1-h postprandial glucose <140 mg/dL or 2-h postprandial glucose <120 mg/dL. If blood glucose targets were not maintained in more than half of measurements during 1 week assessment, insulin treatment was initiated. Demographic characteristics (age, gravida, parity, HbA1C, body mass index (BMI), birthweight), results of the 75-gr OGTT and ultrasonographic parameters including EFT, biparietal diameter (BPD), abdominal circumference (AC), femur length (FL) and deepest vertical pocket of amniotic fluid (DVP) were evaluated. Macrosomia was defined as a birthweight >90th percentile corrected for gestational age and gender. Samsung® HS 70A4D real time ultrasonography system (2017, Seoul, Korea) was used for all patients by the same clinician as described previously19.
Patients whose fetal position was not suitable (the back of the fetus was close to the probe) and patients who did not have appropriate EFT measurements due to maternal morbid obesity were not included in the study. EFT is located along the right ventricular wall. Dimensions of EFT are highest towards the fetal heart apex and thickness decreases towards the base of the heart20,21. Thickest area of epicardial fat was chosen to measure the EFT. In an attempt to standardize the measurement technique as much as possible, images from cardiac long axis views of left outflow tract or short axis view of right outflow tract as close to the level of the aortic valve as possible were utilized (Figure 2). Measurement should be taken at the end of diastole and mean thickness of 3 consecutive measurements should be recorded. Adipose tissue can be easily distinguished from pericardial effusion as it is more echogenic. Furthermore, pericardial fusion-EFT distinction can be made with color Doppler6. In ultrasonographic measurement, calipers should be placed inwardly between epicardium and myocardium.
Data obtained in the study were analyzed using SPSS (Statistical Package for Social Sciences) for Windows 25.0 program. While evaluating data, descriptive statistical methods (number, percentage, min-max values, mean, standard deviation) were used. The normal distribution of data depends on skewness and kurtosis values being between ±3. In the comparison of normally distributed data and quantitative data, independent t-test was used for difference between two independent groups, and one-way analysis of variance (ANOVA) was used for comparing more than two independent groups. Chi-square test was used for categorical variables. The significance level was accepted as 0.05. Since OGTT was not performed in patients with PGDM, ANOVA for OGTT variables was not performed in this group. Independent t-test was used for these variables. Post Hoc-Bonferroni test was applied to determine which group make a difference after a statistically significant result in the comparison of the 3 groups. Correlation test was performed between EFT and other demographic measurements, and Pearson coefficient was checked for data with normal distribution. Receiver-operating-characteristic (ROC) curve analysis was used to calculate cut-off values in differentiating pregnancies with pregestational DM and GDM from normal pregnancies according to fetal EFT value.