Mid-Trimester Cervical Length Screening in Routine Practice: Short-Cervix Prevalence, Preterm Birth and the Shift of the Progesterone Counselling Threshold from 20 to 25 mm in a 15-Year Single-Centre Cohort of 20,168 Singleton Pregnancies

Background/Objectives: Vaginal progesterone reduces preterm birth in women with a short mid-trimester cervix, and the treatment threshold has moved from 15–20 mm to 25 mm; how this change reached everyday practice is rarely documented. We describe cervical length (CL) distribution, short-cervix prevalence, preterm-birth and neonatal outcomes and the evolution of progesterone counselling in routine screening.

Methods

Retrospective cohort of singleton pregnancies with a CL measurement at 16+0–24+6 weeks in one Romanian fetal-medicine centre (2011–2026). CL was measured transabdominally and, when <30 mm, transvaginally (FMF criteria). Documented counselling was extracted from the structured report text by keyword search; delivery outcome was available for 20.3% of pregnancies, so outcome analyses describe the outcome-ascertained subgroup.