Follow-up cervical length in asymptomatic high-risk women and the risk of spontaneous preterm birth

Objective:to determine whether further cervical length shortening by transvaginal ultrasonography in asymptomatic high-risk women with a short cervical length adds additional predictive value for spontaneous preterm birth and perinatal morbidity.study design:women with a history of spontaneous preterm birth, loop electrosurgical excision procedure, cone biopsy or uterine anomaly, who were pregnant with singleton gestations and were found by transvaginal ultrasonography to have a cervical length <3.0 cm at 20 to 28 weeks’ gestation, and who underwent a follow-up cervical length within 3 weeks were evaluated, comparing those with further cervical length shortening (>10%) to those without further shortening. primary outcomes were spontaneous preterm birth <35 weeks’ gestation and perinatal morbidity. secondary outcomes included spontaneous preterm birth <37 weeks, <34 weeks, <32 weeks, birth weight <2500 g, maternal and other neonatal outcomes.result:compared with women without further cervical shortening, those with further shortening were found by univariate analyses to have higher rates of spontaneous preterm birth <35 weeks (34.8 versus 8.5%, p=0.014), <37 weeks (56.5 versus 21.3%, p=0.003), <34 weeks (30.4 versus 2.1%, p=0.001), <32 weeks (21.7 versus 0%, p=0.003), birth weight <2500 g (60.9 versus 17.0%, p<0.0001), neonatal intensive care unit admission (47.8 versus 17.0%, p=0.006) and composite perinatal morbidity (43.5 versus 14.9%, p=0.009). logistic regression revealed the only independent predictors of spontaneous preterm birth <35 weeks were further cervical length shortening (adjusted odds ratio (aor) 5.73; 95% confidence interval (ci) 1.31 to 24.43) and gestational age at short cervical length (aor 0.95; 95% ci 0.91 to 0.99).conclusion:further cervical length shortening in asymptomatic high-risk women with a short cervical length is an important independent predictor of spontaneous preterm birth <35 weeks and perinatal morbidity.