title: Follow-up cervical length in asymptomatic high-risk women and the risk of spontaneous preterm birth.
abstract: 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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Obstetrics and Gynecology, Eastern Health, Memorial University, St John's, Newfoundland, Canada. joan.crane@easternhealth.ca
authors.forename: J M G
authors.initials: JM
authors.lastname: Crane
authors.forename: D
authors.initials: D
authors.lastname: Hutchens
mesh_terms: D000328:Adult; D058070:Asymptomatic Diseases; D054791:Cervical Length Measurement / Q000379:methods*; D002584:Cervix Uteri / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000453:epidemiology; D007234:Infant, Premature; D018743:Perinatal Care / Q000379:methods; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D018566:Pregnancy, High-Risk; D047928:Premature Birth / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D011295:Prenatal Care / Q000379:methods; D012189:Retrospective Studies; D012307:Risk Factors