TOPLINE:

Women with a history of spontaneous preterm birth (sPTB) and a cervical length > 25-30 mm during the midtrimester had approximately threefold higher odds of recurrent sPTB before 37 weeks of gestation than those with a cervical length > 30 mm; however, a change in cervical length from 14 + 0 to 23 + 6 weeks was not associated with recurrent sPTB.

METHODOLOGY:

• Researchers conducted a retrospective cohort study to evaluate whether cervical length shortening is associated with a recurrent sPTB in women with a history of sPTB and a cervical length > 25 mm before 24 weeks of gestation.
• They included 469 singleton pregnancies in women with a prior sPTB before 34 weeks of gestation who had a subsequent singleton pregnancy with multiple cervical length measurements before 24 weeks of gestation, all > 25 mm, from two academic hospitals in Netherlands between February 2005 and September 2021.
• The cervical length was measured transvaginally by experienced sonographers following the Fetal Medicine Foundation guidelines at three timepoints —14 + 0 to 18 + 6, 19 + 0 to 20 + 6, and 21 + 0 to 23 + 6 weeks. Shortening was defined as at least a 1 mm decrease from the prior measurement and was reported using a clinical cutoff of 5 and 10 mm or more.
• The primary outcome was sPTB, defined as birth before 37 weeks of gestation that began with spontaneous contractions or spontaneous rupture of membranes. Researchers assessed the association between cervical length shortening during the second trimester and sPTB before 37, 34, and 28 weeks of gestation.

TAKEAWAY:

• Overall recurrence rates of sPTB were 21.1% before 37 weeks, 9.0% before 34 weeks, and 1.9% before 28 weeks of gestation.
• At 21 + 0 to 23 + 6 weeks, women with a cervical length > 25-30 mm had higher odds of recurrent sPTB before 37 weeks of gestation than those with a cervical length > 30 mm (odds ratio, 3.6; 95% CI, 1.91-6.66).
• The change in cervical length from 14 + 0 to 23 + 6 weeks was not associated with the risk for sPTB before 37, 34, and 28 weeks of gestation; however, the absolute cervical length was strongly linked to recurrent sPTB.

IN PRACTICE:

"The absolute cervical length is more associated with a sPTB than a decrease in cervical length. This study supports the current guidelines which advise to continue serial cervical length measurements at least up to 23 + 6 weeks of gestation," the authors wrote.

SOURCE:

This study was led by Emilie V.J. van Limburg Stirum and Sofie H. Breuking, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands. It was published online on February 23, 2026, in Archives of Gynecology and Obstetrics.

LIMITATIONS:

The retrospective study design may have introduced bias and confounding. The reliance on existing data limited the ability to verify data quality and consistency. The study excluded women with no repeated cervical measurements, which may have introduced selection bias.

DISCLOSURES:

This study did not receive any specific funding. The authors declared having no competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.