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.