Patterns of normal change in cervical length and width during pregnancy in nulliparous women: a prospective, longitudinal ultrasound study
OBJECTIVES: To determine what constitutes normal changes in the uterine cervix visible at transvaginal ultrasound examination from 24 gestational weeks until delivery in nulliparous women delivering at term. DESIGN: Cervical length and width were measured using transvaginal ultrasound, and the inner cervical os was assessed as being closed or open every 2 weeks from gestational week 24 until deliv