EP18.01: Role of cervical length and birthweight in women with history of previous Caesarean section: prediction of early onset of labour before 39 weeks of gestation

Abstract

To evaluate whether the serial cervical length measured by transvaginal ultrasound between 26∼30 weeks and 35∼36 weeks of gestation is predictive of spontaneous early onset of labour in women with history of previous Caesarean section (CS). This study was designed as a retrospective observational study on 223 women with history of previous Caesarean section. The cervical length was measured ultrasonographically at 26–30 weeks and 35–36 weeks of gestation. Of the 223 pregnancies enrolled, 80 (35.9%) developed spontaneous onset of labour before 39 weeks of gestation. The cervical length at 35∼36weeks of gestations was significantly shorter in these women when compared with those delivering after 39 weeks of gestation (24 vs. 31 mm P<0.0001). Serial cervical length between 26∼30 weeks and 35∼36weeks of gestations was significantly larger in early spontaneous labour onset groups (0.89 vs. 0.35mm. p=0.004). Also, the birthweight was significantly lower in early spontaneous labour onset groups (3106 vs 3386g p <0.0001) Multivariate logistic regression analysis showed that cervical length (adjusted odds ratio(aOR) 5.85; 95% confidence interval (CI) 2.696-12.695; P≤0.0001) at 35∼36weeks and birthweight (aOR 1.003(95% CI 1.001-1.004, p<0.0001)were predictors for the onset of labour before 39 weeks of gestation. The area under the receiver-operating characteristics curve for the prediction of early onset of labour was 0.847 (95% CI 0.738-0.950) for cervical length and birthweight as test variable. Cervical length at 35-36 weeks of gestation and birthweights provides information about the likelihood of onset of labour before 39 weeks of gestations in women with history of previous CS and may be useful in individualising the gestational age for elective CS.