Medical data
The following variables were collected from patient medical records: maternal age, parity, pregestational body mass index (BMI), use of in vitro fertilization, chronicity, maternal major comorbidities including pregnancy-associated hypertensive disorders and gestational diabetes mellitus, membrane prolapse beyond external os, manipulation of membranes during the cerclage, cervical dilation in cm at diagnosis, GA at the time of cervical dilation, GA at the time of cerclage, GA at delivery, interval from diagnosis of cervical dilation to delivery, rates of sPTB, rates of PPROM, surgical technique, selection of sutures and additional tocolysis.
GA was determined by evaluating the last menstrual period and crown–rump length measurement on early ultrasound. Chronicity was determined by early ultrasound.
Neonatal outcomes included birth weight, Apgar score at 5 minutes, admission to the neonatal intensive care unit (NICU), severe neonatal complications and neonatal or perinatal mortality.