We unable to include the participants as we expected. Only 1 case included after 4 months of recruitment so we decided to withdrawn the study. This is because of COVID-19 pandemic, result in decreasing in the number of patient visiting our insitute.

To compare the effectiveness of treatment of threatened preterm labor between transvaginal cervical length-based approach and conventional approach (Per vaginal examination)

Inclusion Criteria:

• Pregnant with symptoms of threatened preterm labor which refer to regular uterine contractions at least 1 time in every 10 minutes and persist for 30 minute without cervical dilatation or cervical dilation ≤ 1 cm and < 80% of effacement.
• Age ≥ 18 years
• Singleton pregnancy
• 24 0/7 - 33 6/7 weeks of gestation
• Uneventful antenatal care or low-risk pregnancies

Exclusion Criteria:

• The definitive diagnosis of true labor
• Proceed to the active phase of labor
• Age < 18 years
• Multiple pregnancies
• < 24 or ≥ 34 weeks of gestation
• Fetal chromosomal or structural abnormalities
• Abnormal fetal growth
• Abnormal amniotic fluid
• Evidence of placenta previa
• Significant vaginal bleeding that cannot be ruled out placenta previa
• Evidence of rupture of membranes
• Evidence of intrauterine infection
• Evidence of uterine malformation
• Evidence of lethal fetal malformation
• Unable to communicate or understand the information of the study

Study in pregnant women