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.
Harris Birthright Research Centre for Fetal Medicine, King's College Hospital Medical School, London, UK.
M S
MS
To
C A
CA
Skentou
P
P
Royston
C K H
CK
Yu
K H
KH
Nicolaides
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