Women with a prior early spontaneous preterm birth and a shortened mid-trimester cervical length (less than 25 mm) are at very high risk for having another premature baby. The Vaginal Ultrasound Cerclage Trial is a multicenter, randomized clinical trial designed to determine the efficacy of cerclage (a purse-string suture placed around the uterine cervix) for the prevention of spontaneous preterm birth prior to 35 weeks' gestation. The study will evaluate women at significant risk for recurrent spontaneous preterm birth (those with a prior spontaneous birth at 17 to 32 weeks' gestation) and who have an increased risk based on mid-trimester ultrasound findings of a cervical length less than 25 mm.

The trial will have an observational portion and an interventional portion. In the observational portion, 1,000 women with a history of a spontaneous preterm birth at 17 to 32 weeks' gestation will undergo biweekly vaginal ultrasounds beginning at 16 to 18 weeks' gestation and ending by 22 weeks. Prior research indicates that one third of these women will either have or develop a cervix less than 25 mm long. Women will be seen at a frequency determined by the cervical length (as determined by ultrasound examination starting at 16 weeks' gestation). If cervical length remains greater than 30 mm, the next visits will occur in 2 week intervals until 22.6 weeks' gestation. If the cervical length is 25 mm to 29 mm, the visits will be scheduled weekly. If the cervical length shortens to less than 25 mm, the woman is eligible for randomization, and will undergo one more study visit.

In the interventional portion of the trial, women will be randomized to either cerclage or no cerclage (control group). Randomized women will have weekly contact with a nurse either by phone or in person, whichever is convenient for the woman, until delivery occurs. The woman is followed during the course of her pregnancy and delivery of her infant. Her infant is followed until discharge from the hospital.