Objective: To compare the obstetrics and neonatal outcome of a protocol using the cervical length (CL) measurement with a traditional protocol without CL measurement in the management of threatened preterm labor.

Materials and Methods: The present randomized controlled trial was carried out in Udonthani Hospital between November 2018 and August 2019. One hundred sixteen preterm pregnant women randomly allocated into either a CL group (n=58) or a non-CL group (n=58) were included in this study. CL of less than 3 cm and persistent contractions after one to two hours rest were indications for tocolytic treatment. The proportion of preterm births within 48 hours after treatment, the proportion of tocolytic using cases, and the obstetrics and neonatal outcomes were compared between the groups.

Results: Out of the 58 women in the CL group, 39.7% had a CL of less than 3 cm. Delivery within 48 hours occurred in 8.6% of the CL group compared with 15.5% in the non-CL group, which was not statistically significant. Tocolytic drug was given to 65.5% in the CL group compared with 94.8% in non-CL group (p<0.01). The participants were followed up until delivery and 55 women in the CL group and 57 women in the non-CL group completed the present study. Preterm delivery rate was 36.4% in the CL group compared with 36.8% in the non-CL group (p>0.05). There was no significant difference for the mean gestational age at delivery and neonatal complications for both groups.

Conclusion: CL measurement protocol did not improve the neonatal outcome of threatened preterm labor. However, it reduced unnecessary tocolytic treatment and its associated complication.