Study design and patient selection.
The protocol of this prospective case-control study was approved by the
hospital ethics committee, and written informed consent was obtained
from each participant before participation in the study. All phases of
the study were conducted based on the universal ethical principles of
the Declaration of Helsinki. The study was conducted between July and
December 2019 at the Department of Perinatology, Zekai Tahir Burak
Women’s Health and Research Hospital, Ankara, Turkey.
A total of 80 participants were recruited for the study, 40 of whom were
diagnosed with GDM and 40 healthy pregnant women with the same
gestational age served as the control group. With an effect size of
d=0.5, a margin of error of 5%, and a power of 80% (n1:30, n2:30), at
least 60 samples were deemed adequate by the power analysis performed
with the G*Power 3.0.10 program. All participants were between 28 and 39
weeks of gestation. All demographic and clinical characteristics were
obtained from medical records. Gestational age was confirmed using first
trimester sonographic dating. GDM was diagnosed according to the
criteria of the American College of Obstetricians and Gynecologists
(ACOG) guidelines in a two-stage testing procedure at 24 to 28 weeks of
gestation [1]. After a positive 50g-one-hour oral glucose challenge
test (one-hour glucose level ≥ 140 mg/dl), the diagnosis was made if two
or more glucose levels were above the normal range on the 100
g-three-hour oral glucose tolerance test (fasting glucose level: 95
mg/dl; one-hour glucose level: 180 mg/dl; two-hour glucose level: 155
mg/dl; three-hour glucose level: 140 mg/dl).
Exclusion criteria were abnormal prenatal screening results in the first
and/or second trimester, multiple pregnancies, a history of coexisting
chronic systemic disease, gestational diabetes and other abnormalities
of glucose metabolism, pregnancy complications such as gestational
hypertension, placental abruption, fetal growth restriction, premature
rupture of membranes, and chorioamnionitis. Fetuses with congenital or
chromosomal abnormalities were not included in the study. In addition,
participants who had a single high glucose level on 100g OGTT were not
included in the control group because some of them may have had insulin
resistance or impaired glucose metabolism. A total of 20 individuals in
both groups were excluded because of obstetric complications that
developed during follow-up.
Ultrasound and Doppler Measurements All sonographic examinations were
performed transabdominal using the Voluson 730 Expert sonography unit
(GE Healthcare, Milwaukee, WI) with a 3.5-MHz convex transducer by a
single investigator with 10 years of experience in obstetric sonography
who was blinded to all clinical parameters. Sonographic assessment of
fetal anatomy, maximal measurement of deepest vertical amniotic fluid
(MVP) pocket, fetal biometry, estimated fetal weight (EFW), and
umbilical artery Doppler measurements (umbilical artery RI, resistance
index; PI, pulsatility index; S/D, systolic/diastolic ratio) were
performed according to the guidelines of the International Society of
Ultrasound in Obstetrics and Gynecology and the Institute of Ultrasound
in Medicine.