What cervical length measurement suggests a higher likelihood of preterm delivery?

Cervical length is a significant predictor of preterm delivery, particularly in pregnancies at risk for such outcomes. A cervical length measurement of less than 15 mm indicates a substantially elevated risk for preterm birth. This threshold is based on research demonstrating that shorter cervical lengths correlate with an increased likelihood of cervical incompetence, which can lead to premature labor and delivery.

In clinical practice, measurements of cervical length are often taken via transvaginal ultrasound during the second trimester to assess the risk of preterm delivery. A cervical length below 15 mm is considered a critical warning sign, signaling the need for close monitoring and potential intervention such as prophylactic measures or magnesium sulfate for neuroprotection of the fetus if preterm delivery appears imminent.

The other cervical length measurements, such as those greater than 30 mm, equal to 20 mm, or between 20 mm and 30 mm, are generally associated with a lower risk for preterm delivery. These longer cervical lengths provide more structural support and resilience to the growing fetus, reducing the likelihood that the uterus will contract prematurely. Thus, while cervical lengths greater than 30 mm and those within the range of 20 mm to 30 mm represent more favorable conditions regarding preterm labor risk, the critical