Prediction of patient-specific risk of early preterm delivery using maternal history and sonographic measurement of cervical length: a population-based prospective study.
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.
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Harris Birthright Research Centre for Fetal Medicine, King's College Hospital Medical School, London, UK.
Skentou
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Royston
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Yu
C K H
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Nicolaides
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KH
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000886:Anthropometry; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D003127:Colposcopy; D005260:Female; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D007752:Obstetric Labor, Premature / Q000175:diagnosis*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011336:Probability; D011446:Prospective Studies; D044469:Racial Groups; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D012907:Smoking; D016216:Ultrasonography, Prenatal