Gestational age‐related changes in cervical gland length in normal singleton pregnancies from 17 to 36 weeks of gestation

Abstract

Aim To determine the gestational age‐related changes in cervical gland length in relation to cervical length (CL) in normal singleton pregnancies. Methods We studied 363 women with an uncomplicated singleton pregnancy (188 nulliparous and 175 multiparous women with one or more previous transvaginal deliveries). A total of 1138 cervical gland and CLs were measured longitudinally at 17–36 weeks of gestation using transvaginal ultrasonography along the curvature from the external os to the lower uterine segment and the internal end of the cervical gland area (CGA), respectively. Gestational age‐related changes in cervical gland and CLs and their relationships were analyzed using a linear mixed model. Results Cervical gland and CLs decreased in different ways with advancing gestation depending on parity, and their changes were related to each other. The CGAs in nulliparous women were longer than those in multiparous women at 17–25 weeks of gestation (p < 0.05), but with no differences thereafter. CLs in multiparous women were different from those in nulliparous women at 17–23 and 35–36 weeks (p < 0.05), but there were no differences at 24–34 weeks. The cervix did not shorten compared with the CGA throughout the observational periods in nulliparous and multiparous women. Conclusions Shortening of the cervix indicates changes to the lower uterine segment in normal pregnancies. The cervical gland region can be a useful marker representing the true cervix beyond 25 weeks of gestation, irrespective of parity.