Small changes, big impact Managing the short cervix

This thesis focuses on spontaneous preterm birth (sPTB), a major cause of neonatal morbidity and mortality worldwide. The cervix plays a central role in this context, both as a potential cause of preterm birth and as a marker of underlying pathological processes. Measurement of cervical length (CL) during pregnancy is a strong predictor of sPTB and forms the basis for risk stratification and preventive treatment. The aim of this thesis was to evaluate the role of CL measurements and CL-based interventions in pregnant women with different baseline risks of sPTB.
In pregnant individuals without a prior sPTB, universal CL screening proved to be more effective than risk-based screening, as a targeted approach misses many individuals with a short cervix. CL measurements primarily identified women at increased risk of very early preterm birth (<32 weeks). In randomized studies, a cervical pessary was not more effective than vaginal progesterone in either singleton or multiple pregnancies with a short cervix.
In pregnant individuals with a history of sPTB, the risk of recurrence remained elevated regardless of CL or the gestational age of the previous preterm birth. Also, a CL of 26–30 mm was associated with a clearly increased risk of recurrence. Physical examination-indicated cerclage before 24 weeks significantly prolonged pregnancy compared with expectant management. In addition, a pessary was not found to be non-inferior to cerclage in women at high risk of sPTB.
This thesis underscores the central importance of cervical length measurements in both the prediction and prevention of sPTB. The findings support the use of universal CL screening during pregnancy as a standard component of preterm birth prevention.