Gestational Trimester-Specific Changes in Cervical Length and Their Predictive Value for Preterm Delivery

Area of Science:

• Obstetrics and Gynecology
• Maternal-Fetal Medicine
• Reproductive Health

Background:

• Cervical length (CL) is a key indicator in pregnancy.
• Understanding gestational age-specific CL variations is crucial for predicting preterm delivery (PTD).

Purpose of the Study:

• To analyze gestational age-specific changes in cervical length (CL).
• To assess the predictive capability of CL for preterm delivery (PTD) across different trimesters.

Main Methods:

• Retrospective longitudinal study of 8659 women with singleton live births.
• CL measurements at ≤19⁺⁶, 20-24⁺⁶, and 28-33⁺⁶ weeks gestation.
• Receiver operating characteristic curve analysis and log-rank tests to evaluate CL's predictive ability for PTD.

Main Results:

• Cervical length (CL) demonstrated significant shortening between 28-33⁺⁶ weeks gestation.
• Differences in CL distribution between PTD and term delivery groups were evident by 20-24⁺⁶ weeks.
• CL's predictive value for PTD increased with gestational age, with specific thresholds identified for different gestational windows.

Conclusions:

• Cervical length (CL) progressively decreases with advancing gestational age.
• CL is a potent predictor of preterm delivery (PTD) after 20 weeks gestation.
• A revised definition of a short cervix (<10 mm) in late pregnancy (28-33⁺⁶ weeks) is proposed.