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Late Cervical Shortening following Midtrimester Screening: Associations with Obstetric History and Risk of Preterm
Raneen Abu Shqara1,2, Maisa Assy3, Lior Lowenstein4,3
1Raya Strauss Wing of Obstetrics and Gynecology, Galilee Medical Center, Nahariya, Israel, rabushqara@gmail.com.
Gynecologic and Obstetric Investigation
|May 25, 2026
Summary
Late-onset cervical shortening after normal midtrimester screening significantly increases the risk of spontaneous preterm birth (sPTB) and adverse neonatal outcomes. Gestational age-specific cervical length thresholds can improve risk stratification for personalized management.
Area of Science:
- Maternal-fetal medicine
- Obstetrics
- Perinatology
Background:
- Midtrimester cervical length screening typically identifies pregnancies at low risk for preterm birth.
- Late-onset cervical shortening, diagnosed after the midtrimester, may represent a distinct risk factor for adverse pregnancy outcomes.
Purpose of the Study:
- To evaluate the clinical significance of late-onset cervical shortening (diagnosed 24.0-34.0 weeks gestation) following normal midtrimester screening.
- To assess the association of late cervical shortening with spontaneous preterm birth (sPTB) and neonatal morbidity.
- To determine if obstetric history modifies the risk associated with late cervical shortening.
Main Methods:
- Retrospective cohort study of 500 singleton pregnancies with normal midtrimester cervical length (CL) who subsequently developed cervical shortening (<25 mm) between 24.0 and 34.0 weeks.
- Patients categorized into CL groups: <10 mm, 11-15 mm, and 16-25 mm, stratified by gestational age at diagnosis.
- Primary outcome: sPTB <37 weeks. Secondary outcomes: sPTB <34 and <32 weeks, neonatal morbidity. Multivariable logistic regression and ROC curve analysis used for risk assessment and threshold determination.
Main Results:
- Significant association found between degree of late cervical shortening and sPTB rates (<37 weeks): 75.0% for CL <10 mm, 52.5% for CL 11-15 mm, and 25.0% for CL 16-25 mm (p<0.001).
- Similar trends observed for sPTB <34 and <32 weeks.
- Obstetric history influenced risk in the 21-25 mm CL group (p=0.041), but not in shorter CL groups. Gestational age-specific CL thresholds for predicting sPTB <37 weeks were identified (e.g., 22 mm at 24.0-27.6 weeks, AUC 0.69).
Conclusions:
- Late-onset cervical shortening after normal midtrimester screening is a significant predictor of spontaneous preterm birth and adverse neonatal outcomes.
- The degree of cervical shortening and obstetric history are crucial factors in risk stratification, especially for moderate late shortening.
- Gestational age-specific cervical length thresholds can aid in identifying high-risk pregnancies for tailored surveillance and management.
