Materials and methods
The study was conducted on a multicenter material of placental probes
from the Obstetrics Department of the Provincial Hospital of Przemyśl,
Department of Perinatology of the Medical University Bialystok, and
Obstetrics Clinic of the Medical University of Lublin. Using CinCalc.com
sample size calculator the minimal sample size was established on 34
women20. The material was taken from 150 women who
gave birth in the period from March 2004 to December 2012. 115 women
were diagnosed with premature delivery and were included in the Study
Group, 35 women had a delivery at term and were allocated to the Control
Group.
The following inclusion criteria were used: spontaneous deliveries
concluded with vaginal delivery or with an emergency Cesarean section
between 22. gestational weeks and 36. gestational weeks and 6 days. The
control group consisted of women who had a spontaneous delivery between
37 gestational weeks and 40 gestational weeks and 6 days were included.
Patients with diagnosed complications during the current pregnancy, as
multiple gestations, anemia, intrahepatic cholestasis of pregnancy,
acute fatty liver of pregnancy, chronic kidney disease, autoimmune
disorders, immunodeficiency, group of placentae previa, fetal growth
restriction, oligohydramnios, polyhydramnios and other rare
complications not otherwise described were excluded from the study.
Fetal chromosomal abnormalities, fetuses with diagnosed anatomical
abnormalities during the current pregnancy, pregnancies conceived using
in vitro fertilization, and intrauterine fetal demise were also excluded
from the study.
This study was in accordance with the STROBE Statement - Checklist of
items of cohort studies, which can be found in the appendix of the
study21.
Every patient was informed about the aim of the study, its process, and
agreed to it before the involvement in the study. The study had received
the approbation of the Bioethical Committee of the University of Rzeszów
(Nr. 05/10/2020).