Normal cervical changes in parous women during the second half of pregnancy--a prospective, longitudinal ultrasound study.

Objective: To determine what constitutes normal cervical changes during the second half of pregnancy in parous women delivering at term.

Design: The study comprises 21 healthy, pregnant parous women who all gave birth at term. They were examined with transvaginal ultrasound every two weeks from 24 gestational weeks until delivery.