The capacity of mid-pregnancy cervical length to predict preterm birth in low-risk women: A national cohort study

Jeanine Van Der Ven, Melanie A. Van Os, Brenda M. Kazemier, Emily Kleinrouweler, Corine J. Verhoeven, Esteriek De Miranda, Aleid G. Van Wassenaer-Leemhuis, Petra N. Kuiper, Martina Porath, Christine Willekes, Mallory D. Woiski, Marko J. Sikkema, Frans J M E Roumen, Patrick M. Bossuyt, Monique C. Haak, Christianne J M De Groot, Ben W J Mol, Eva Pajkrt

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Introduction. We investigated the predictive capacity of mid-trimester cervical length (CL) measurement for spontaneous and iatrogenic preterm birth. Material and methods. We performed a prospective observational cohort study in nulliparous women and low-risk multiparous women with a singleton pregnancy between 16+0 and 21+6 weeks of gestation. We assessed the prognostic capacity of transvaginally measured mid-trimester CL for spontaneous and iatrogenic preterm birth (<37 weeks) using likelihood ratios (LR) and receiver-operating-characteristic analysis. We calculated numbers needed to screen to prevent one preterm birth assuming different treatment effects. Main outcome measures were preterm birth <32, <34 and <37 weeks. Results. We studied 11 943 women, of whom 666 (5.6%) delivered preterm: 464 (3.9%) spontaneous and 202 (1.7%) iatrogenic. Mean CL was 44.1 mm (SD 7.8 mm). In nulliparous women, the LRs for spontaneous preterm birth varied between 27 (95% CI 7.7-95) for a CL ≤ 20 mm, and 2.0 (95% CI 1.6-2.5) for a CL between 30 and 35 mm. For low-risk multiparous women, these LRs were 37 (95% CI 7.5-182) and 1.5 (95% CI 0.97-2.2), respectively. Using a cut-off for CL ≤ 30 mm, 28 (6.0%) of 464 women with spontaneous preterm birth were identified. The number needed to screen to prevent one case of preterm birth was 618 in nulliparous women and 1417 for low-risk multiparous women (40% treatment effect, cut-off 30 mm). Conclusion. In women at low risk of preterm birth, CL predicts spontaneous preterm birth. However, its isolated use as a screening tool has limited value due to low sensitivity.

Original languageEnglish
Pages (from-to)1223-1234
Number of pages12
JournalActa Obstetricia et Gynecologica Scandinavica
Issue number11
Publication statusPublished - Nov 2015


  • Cervical length measurement
  • low-risk population
  • preterm birth

ASJC Scopus subject areas

  • Obstetrics and Gynaecology

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