Prediction of patient-specific risk of early preterm delivery using maternal history and sonographic measurement of cervical length: a population-based prospective study

Ultrasound Obstet Gynecol. 2006 Apr;27(4):362-7. doi: 10.1002/uog.2773.


Objective: To develop a model for calculating the patient-specific risk of spontaneous early preterm delivery by combining maternal factors and the transvaginal sonographic measurement of cervical length at 22 + 0 to 24 + 6 weeks, and to compare the detection rate of this method to that achieved from screening by cervical length or maternal characteristics alone.

Methods: This was a population-based prospective multicenter study involving 40,995 unselected women with singleton pregnancies attending for routine hospital antenatal care in London, UK. Complete follow-up was obtained from 39,284 (95.8%) cases. The main outcomes were detection rate, false-positive rate and accuracy of predicting spontaneous delivery before 32 weeks' gestation.

Results: Spontaneous delivery before 32 weeks occurred in 235 (0.6%) cases. The detection rate of screening for early preterm delivery, at a fixed false-positive rate of 10%, was 38% for maternal factors, 55% for cervical length and 69% for combined testing. There was good agreement between the model estimates and the observed probabilities of preterm delivery.

Conclusions: This study provides a model that can give an accurate patient-specific risk of preterm delivery. The detection rate of screening by a combination of maternal factors and the measurement of cervical length was substantially higher than that of screening by each method alone.

Publication types

  • Multicenter Study

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Anthropometry
  • Cervix Uteri / diagnostic imaging*
  • Colposcopy
  • Continental Population Groups
  • Female
  • Humans
  • Logistic Models
  • Middle Aged
  • Obstetric Labor, Premature / diagnosis*
  • Pregnancy
  • Pregnancy Trimester, Second
  • Probability
  • Prospective Studies
  • Risk Assessment / methods
  • Sensitivity and Specificity
  • Smoking
  • Ultrasonography, Prenatal*