Twin transvaginal cervical length at 16-20 weeks and prediction of preterm birth.

Objective: Our objective was to determine if transvaginal cervical length at 16-20 weeks is predictive of preterm birth <34 weeks in a large cohort of twin pregnancies.

Study Design: This is a secondary analysis from a randomized trial of 17 alpha-hydroxyprogesterone caproate in twins to prevent preterm birth. Transvaginal cervical length was performed at 16-20-week gestation.