Results
A total of 502 patients, including 161 pregnant women with PGDM, 171
pregnant women with GDM and 170 controls, were evaluated. The PGDM group
consisted of 98 (60.8%) women with Type 1 and 63 (39.2%) women with
Type 2 DM. Demographic characteristics and ultrasound findings of three
groups were showed in Table 1. Patients in PGDM group were significantly
older than both control and GDM groups (p=0.002) (Table 1). FPG, 1-h and
2-h blood glucose values of patients in GDM group were found to be
significantly higher than control group (p<0.001). HbA1C
values were significantly higher in both GDM and PDGM groups compared to
control group (p<0.001). As expected, HbA1c values of patients
with PGDM were significantly higher than those with GDM (p=0.021). Body
mass index was significantly higher in PGDM group compared to control
group (p=0.047). In ultrasound measurements, AC and DVP were found to be
significantly higher in PGDM and GDM groups compared to control group
and also significantly higher in PGDM group compared to GDM group
(p<0.001).
The mean of EFT measurements were found to be 1.19 ± 0.049 mm, 1.40 ±
0.082 mm and 1.47 ± 0.083 mm for the control, GDM and PGDM groups,
respectively (Table 1). There was a significant difference between all
three groups in terms of EFT (p<0.001). After adjusting by
Bonferroni correction, it was observed that the mean EFT of control
group was lower than the mean values of GDM and PGDM groups.
Furthermore, the mean EFT of PGDM group was higher than the mean EFT of
GDM group (p<0.001). Comparison of the mean values of EFT
using a box plot among three groups were demonstrated in Figure 3a.
Correlation analysis was performed to test the relationship between EFT
and demographic characteristics of patients (Table 2). There was a
statistically significant weak positive correlation between EFT and
maternal age (r=0.184, p<0.001), FPG (r=0.188, p=0.005) and
DVP (r=0.332, p<0.001), moderate positive correlation between
EFT and fetal AC (r=0.422, p<0.001), HbA1C (r=0.559,
p<0.001) and strong positive correlation between EFT and
1st hour (r=0.650, p<0.001) and
2nd hour glucose values (r=0.719, p<0.001).
ROC analysis was performed to identify optimal cut-off points in
differentiating pregnancies with GDM and pregestational DM from normal
pregnancies (Figure 3b,c). The ROC curve of the multivariate logistic
regression model for the diagnosis of GDM demonstrated EFT with other
variables (FPG, 1hPG, 2hPG, HbA1c, AC and DVP) have an AUC of (1.000,
95% CI 1.000-1.000), which is larger than when using the individual
factors of EFT (0.985, 95% CI 0.973-0.997), FPG (0.643, 95% CI
0.565-0.720), 1hPG (0.956, 95% CI 0.927-0.984), 2hPG (0.976, 95% CI
0.953-0.999), HbA1c (0.902, 95% CI 0.861-0.944), AC (0.696, 95% CI
0.628-0.764) and DVP (0.669, 95% CI 0.595-0.742). The ROC curve of the
multivariate logistic regression model for the diagnosis of PGDM
demonstrated EFT with other variables (HbA1c, AC and DVP) have an AUC of
(1.000, 95% CI 1.000-1.000), which is larger than when using the
individual factors of EFT (0.999, 95% CI 0.998-1.000), HbA1c (0.934,
95% CI 0.902-0.967), AC (0.858, 95% CI 0.810-0.906) and DVP (0.814,
95% CI 0.756-0.873). Using a cut-off level of 1.27 mm, EFT diagnosed
GDM with a sensitivity of 94% and specificity of 95% (AUC:0.95 [95
CI 0.973-0.997]). Furthermore, using a cut-off level of 1.3 mm, EFT
diagnosed PGDM with a sensitivity of 97.3% and specificity of 98.2%
(AUC:0.999 [95 CI 0.998-1.000]). We also performed a ROC curve
analysis for assessing the performance of fetal EFT value in predicting
macrosomia. The AUC was 0.945 (95% CI 0.912-0.979) for macrosomia. The
optimal fetal EFT threshold for predicting macrosomia was found as 1.36
mm, with a sensitivity of 93.4% and specificity of 95.8%. We did not
calculate inter-observer reproducibility for EFT because all
measurements were obtained by a single clinician. However,
intra-observer analysis demonstrated good repeatability and
reproducibility of EFT. The interclass correlation coefficient of
intra-observer reproducibility for EFT measurement was 0.755 (95 % CI
0.526-0.984). Intra-observer variability of measurements of EFT was
found to be 0.5 ± 0.4 mm.