This study was done to evaluate transvaginal ultrasonographic measurement of cervical length at 20 to 24 weeks and 37 weeks as a predictor of prolonged pregnancy (defined as a pregnancy that extended beyond 41+2 weeks of gestation [289 days]) in nulliparous women. This prospective observational study enrolled 149 consecutive nulliparous women with singleton gestation at 37 weeks. Cervical length was measured by transvaginal ultrasonography at 20 to 24 weeks and 37 weeks. Cervical length at 37 weeks, but not at 20 to 24 weeks, was significantly longer in women delivered at >41+2 weeks than in those delivered at < or =41+2 weeks (p<0.005). There was a significant correlation between cervical length at 37 weeks and gestational age at delivery (Pearson correlation coefficient, r=0.387, p<0.0001). In the receiver operating curve, the best cut-off value of cervical length at 37 weeks for the prediction of prolonged pregnancy was 30 mm, with a sensitivity of 78% and a specificity of 62%. Cervical length assessed by transvaginal ultrasonography at 37 weeks can predict the likelihood of prolonged pregnancy in nulliparous women. However, there is no association between cervical length at 20 to 24 weeks and the occurrence of prolonged pregnancy.
Vagina ; ROC Curve ; Prospective Studies ; Pregnancy, Prolonged/*diagnosis ; Pregnancy ; Humans ; Gestational Age ; Female ; Cervix Uteri/*anatomy & histology/*ultrasonography ; Adult

OBJECTIVETo observe Chinese women's cervical physiological changes by transvaginal ultrasound.

METHODS637 normal female volunteers were studied. Cervical length, width and canal width were measured by transvaginal ultrasound. Cervical length multiplied by width was the biggest vertical section area of cervix(cervical area).

RESULTSThe cervical length, width, area and canal width in the menopausal women were significant smaller than that in the un-menopausal women (P < 0.0001). Multinomial logistic regression showed that cervical changes were mainly affected by menopause year, gestation and para. The cervical length, width, area and canal width were negative correlated with menopause year significantly. The cervical and canal width were positive correlated with gestation. The regressive equation was Cervical area (cm2) = 3.69 + 0.23 Gastation -0.16 Menopause year.

CONCLUSIONSCervical physiological changes are mainly affected by the menopause year, gestation and para. The menopause year is the most important factor in the cervical physiological changes.

Adult ; Aged ; Anthropometry ; methods ; Asian Continental Ancestry Group ; Cervix Uteri ; anatomy & histology ; diagnostic imaging ; physiology ; Female ; Humans ; Menopause ; Middle Aged ; Reference Values ; Regression Analysis ; Ultrasonography