Midtrimester Cervical Length in Low-Risk Nulliparous Women for the Prediction of Spontaneous Preterm Birth: Should We Consider a New Definition of Short Cervix?

Abstract

Objective The study aimed to estimate the predictive value of midtrimester cervical length (CL) and the optimal cut-off of CL that should be applied with asymptomatic nulliparous women for the prediction of spontaneous preterm birth (sPTB). Study Design This is a prospective cohort study of asymptomatic nulliparous women with a singleton gestation. Participants underwent CL measurement by transvaginal ultrasound between 20 and 24 weeks of gestation. The participants and their health care providers remained blinded to the results of CL measurement. The primary outcomes were sPTB before 35 weeks and sPTB before 37 weeks. Receiver operating characteristics (ROC) curve analyses were performed. Analyses were repeated by using multiples of median (MoM) of CL adjusted for gestational age. Results Of 796 participants, the mean midtrimester CL was 40 ± 6 mm with a 1st, 5th, and 10th percentile of 25, 29, and 32 mm, respectively. ROC curve analyses suggest that a cut-off of 30 mm was the optimal CL to predict sPTB before 35 weeks (area under the ROC curve [AUC]: 0.70, 95% confidence interval [CI]: 0.56–0.85) and before 37 weeks (AUC: 0.70, 95% CI: 0.59–0.80). Midtrimester CL <30 mm could detect 35% of all sPTB before 35 weeks at a false-positive rate of 5% (relative risk: 9.1, 95% CI: 3.5–23.5, p < 0.001). We observed similar results using a cut-off of CL <0.75 MoM adjusted for gestational age. Conclusion A midtrimester CL cut-off of 30 mm (instead of 25 mm), or CL less than 0.75 MoM, should be used to identify nulliparous women at high risk of sPTB. Key Points

Uterocervical angle and cervical length measurements for preterm birth prediction in low-risk singleton pregnant women: A prospective cohort study

“…Additionally, Sawaddisan et al [16] reported that a UCA ≥ 110° measured later than 19.5 weeks of gestation corresponded to an 83.3% sensitivity for predicting spontaneous PTB. A study conducted by Paul Guerby et al [31] revealed that a mid-trimester CL < 30 mm could detect 35% of all spontaneous PTBs before 35 weeks gestation at a false-positive rate of 5% in low-risk nulliparous women. It is important to note that their study included only women with no previous pregnancies, and ultrasound was conducted between 20 and 24 weeks gestation.…”

Prediction of Preterm Birth with the Uterocervical Angle in Singleton Pregnancies Treated with a Cervical Pessary

“…Risk factors include maternal, fetal, biological and genetic variables [9,10]. While the predictive value of cervical length measurement by transvaginal ultrasound (TVS) has been established [11], identification of women at risk of spontaneous PTB by other techniques remains a major challenge [12][13][14].…”

“…Risk factors include maternal, fetal, biological, and genetic variables [9,10]. While the predictive value of cervical length measurement by transvaginal ultrasound (TVS) has been established [11], the identification of women at risk of spontaneous PTB by other techniques remains a major challenge [12,13,14]. Accordingly, cervical shortening is the most commonly used inclusion criterion for trials evaluating the prevention of preterm birth in singleton pregnancies by placement of a cervical pessary.…”

Predicting Preterm Birth with Strain Ratio Analysis of the Internal Cervical Os: A Prospective Study

“…Recently, some authors have questioned the predictive performance of a short cervical length of less than 30 mm compared to that of less than 25 mm and suggested that a cut-off of 30 mm in the second trimester of pregnancy may more accurately predict the risk of PTB before 35 and 37 weeks of gestation (AUC: 0.70) [ 19 ]. However, the majority of observational studies reported a cut-off of 2.5 cm [ 20 , 21 , 22 ], which demonstrated a moderate predictive performance.…”