Background

Preterm birth is associated with significant mortality and morbidity for mothers and babies. Women are identified as high risk for preterm birth based on either previous medical/pregnancy history or on ultrasound assessment of the cervix. Women identified as high risk can be offered a cervical cerclage (a purse string stitch) around the cervix (neck of the womb) to reduce the risk of preterm birth. In women who have a cervical cerclage, the procedure can be performed using either a monofilament (single-stranded) or braided (woven) suture material. Both suture materials are routinely used for cervical cerclage and there is uncertainty as to which is superior.
Methods

A multicentre, open, randomised controlled superiority trial of 2050 women presenting at obstetric units, deemed to be at risk of preterm birth and already scheduled to have a cervical cerclage as part of their standard care. Inclusion criteria include singleton pregnancies and an indication for cervical cerclage for either a history of three or more previous mid-trimester losses or premature births (≤ 28 weeks), insertion of cervical sutures in previous pregnancies, a history of mid trimester loss or premature birth with a (current) shortened (≤ 25 mm) cervix, or women whom clinicians deem to be at risk of preterm birth either by history or the results of an ultrasound scan. Exclusion criteria include women who have taken part in C-STICH previously, are aged less than 18 years old at the time of presentation, require a rescue cerclage, and are unwilling or unable to give informed consent and in whom a cerclage will be placed by any route other than vaginally (e.g. via an abdominal route). Following informed consent, women are randomised on a 1:1 basis to either monofilament or braided suture, by minimisation. The primary outcome is pregnancy loss (miscarriage and perinatal mortality, including any stillbirth or neonatal death in the first week of life), and secondary outcomes include the core outcome set for preterm birth trials.
Discussion

Optimising established interventions to prevent preterm birth is important in reducing perinatal mortality rates.