Both signed written informed consent from all participants and Ethical Committee approve from the Erciyes University School of Medicine was obtained (no: 2019/652). This study was performed at the perinatology clinic of the Erciyes University School of Medicine and classified as prospective, cross sectional and case-controlled. This study has not been published elsewhere.
Participants of the Study
All participants (n=105) of this study were followed up in our clinic after detection of heart beat to delivery time. Gestational week of study population were calculated via using last menstrual date. Gestational age was calculated according to first trimester ultrasound reports in patients who did not remember the date of their last menstrual period. All volunteers were delivered via scheduled caesarean section at the 39th weeks of gestation with cephalic presentation due to previous caesarean section.
According to type of diabetes participants were separated into 3 groups; (1) GDM group (n=35), (2) PGDM group (n=35), and (3) healthy non-diabetic control group (n=35). All volunteers in GDM and healthy non-diabetic control group; were screened by 75 gr OGTT after 12 hours fasting between 24th and 28th weeks of gestation. Upper limits of fasting, first and second hour after 75 gr glucose administration were 92, 180 and 153 mg/dL, respectively12. Above this threshold, patients were diagnosed as GDM. All participants in GDM group received diet and exercise therapy. Then they re-evaluated for glucose levels both fasting and post-prandial second hour. Upper limits of fasting and post-prandial second hour were 95 mg/dl and 120 mg/dl respectively. We only included insulin required participants in GDM group. Patients in PGDM group received examinations by an ophthalmologist and a nephrologist for retinopathy and nephropathy at the end of second trimester (28th weeks of gestation) and 37th weeks of gestation. Moreover patients in PGDM group were classified according to Sacks and Metzger definition and all volunteers in this group were Type 1 insulin depended DM without vascular complications13.
Exclusion Criteria
All participants were examined in detail for fetal abnormalities and received toxoplasma, rubella and cytomegalovirus tests at the 21th weeks of gestation. In the presence of any abnormality or positive test results, they were not accepted suitable for the study. Because fetal sex is a confounder, only volunteers with male fetuses were included to the study. Patients with maternal fever, retinopathy, nephropathy,labor pain, non- cephalic presentation, female fetuses, preeclampsia/eclampsia, intrauterine growth retardation, oligohydroamnios, membrane rupture, chronic systemic diseases, chromosomal or fetal anomaly, twin gestation or more, placenta accereata, increata and percreata, intrahepatic cholestasis of pregnancy were excluded from the study. Among volunteers who use steroid, narcotic, sedative, tobacco, alcohol or anti-psychotic were eliminated. Patients in PGDM group received examinations by an ophthalmologist and a nephrologist for retinopathy and nephropathy at the end of second trimester and 37th weeks of gestation. If diabetic volunteers complicated with retinopathy and nephropathy, these patients were not included into the study. Additionally volunteers who were not capable of achieving normal glucose levels with insulin therapy were not included to the study in patients with PGDM and GDM.
Methods of Diaphragmatic Evaluation and DUSG Timing
An obstetrician aimed to obtain horizontal views of the both left and right diaphragm and measure angle of costodiaphragmatic sinus during examination. Diaphragm consisting of three layers; two echogenic outher layers (pleura and peritoneum) and a non echogenic middle layer (central layer). Video records of diaphragmatic examinations both inspiration and expiration states were obtained from all volunteers by an obstetrician (FO) who was blinded to the diagnosis of the volunteers. Then measurements were performed by reviewing records frame by frame. We obtained thickness of fetal diaphragm (DT) at two time point of respiratory cycle (end-inspiration thickness and end-expiration thickness of fetal diaphragm). Both right and left diaphragm have different movement ability due to the position of liver thus all examinations were performed bilaterally and measurements were illustrated as mean values of both sides. In the presence of gasping or ‘picket-fence’breathing of fetus FO did not evaluate that respiratory cycle. All volunteers with cephalic presentation were examined at 37 th weeks of gestation after ruling out nephropathy and retinopathy.
Measurement of other diaphragm parameters
During expiration and inspiration phases of respiratory cycle, diaphragm moves highest and lowest points in fetal chest. The average distances between highest and lowest points of diaphragm on two respiratory cycles were recorded and calculated. Distance between these two points illustrates the ability of diaphragmatic movement and it is called diaphragmatic excursion (DE). We evaluated another diaphragmatic function marker ‘’diaphragm thickening fraction (DTF)’’ by using a formula (end-inspiration thickness- end-expiration thickness/end-expiration thickness×100)14. Then costodiaphragmatic angle (CDA) was measured on the same video frame during inspiration and expiration phases of respiration.
Other parameters
None of the volunteers had fetal distress and all volunteers underwent planned caesarean section at the 39th weeks of gestation with general anesthesia due to previous uterine scar. For determining fetal lactate, pH, oxygen and carbon dioxide (pO2, pCO2, sO2), levels, arterial cord blood obtained after expulsion of the fetus. Apgar scores, fetal hypoxia, hypotonia, transient tachypnea, mild respiratory distress syndrome, NICU requirement, and other factors were evaluated by a pediatrician. An author (Çİ) collected required demographic and clinical data before USG examination.
Determining sample size and Statistical analysis
For calculating sample size means, standard deviations and reference values were taken from the article “Adverse fetal outcomes in patients with IUGR are related with fetal diaphragm evaluation parameters” 14. We found 29 volunteers necessary when we assumed that power = 0,80 and alpha = 0,05. Because of possible data loss and dropouts, 36 volunteers were included in the study. We excluded 1 volunteer for each group.
To test the normality assumption of the data, Shapiro-Wilk test was used. Variance homogeneity assumption was tested with Levene test. Values are expressed as mean ± standard deviation, median (25th percentile-75th percentile) or n(%). One-Way ANOVA, Chi –Square and Kruskal–Wallis H test were performed for the comparison of differences between groups. Tukey, ZandMann-Whitney U test were used for the multiple comparisons. p<0.05 probability value was considered as statistically significant. All calculations were made via using PASW Statistics 18 software.