OC17.04: QP screening study: maternal risk factors associated with a short mid‐pregnancy cervical length in singletons

Mid-pregnancy short cervical length (CL) ≤35mm has been associated with increased risk for spontaneous preterm birth (sPTB) in singleton pregnancies. However, CL screening is not universal and targeted risk-profiles are not yet established. In this prospective cohort study we aim to identify risk factors for a short mid-pregnancy CL. We performed a multicentre prospective cohort study in 25 hospitals and midwifery practices in the Netherlands. We included low-risk, asymptomatic women with a singleton pregnancy undergoing a transvaginal mid-trimester CL measurement during the fetal anomaly scan between 18+0 -22+0 weeks of gestation. The primary outcome is the association between maternal and obstetric characteristics for a CL ≤ 35mm. Secondary outcomes included the association for a CL ≤ 25mm and a multivariable logistic regression was performed. Odds ratio (OR) calculation with a 95% confidence interval (CI) and binomial logistic regression analyses were used to identify the associations. Overall, 19,364 women were included in analysis of which 2031 (10.5%) had a CL ≤35mm and 269 (1.4%) a CL < 25mm. Multiple maternal and obstetrical characteristics were individually significantly associated with a short cervical length. In a multivariable logistic regression nulliparity (OR 1.9, CI 1.3 – 2.7) and cervical excisional procedures (OR 3.2, CI 1.8 – 5.5) remained statistically significant. Similar results were found for nulliparity (OR1.3, CI 1.0 – 1.7) and cervical excisional procedures (OR 5.1, CI 3.7 – 7.2) in women with a CL < 25mm. Nulliparity, a history of cervical excisional procedures and uterine excavation with curettage are associated with increased odds of short midtrimester CL < 35mm. We advocate for the implementation of universal CL screening during pregnancies, with a particular emphasis on screening women with known risk factors. This facilitates appropriate interventions and personalised care for those at higher risk for sPTB.