Preterm birth refers to a delivery that occurs before 37 weeks of gestation. Identification of those who will eventually deliver in the preterm period is very important. However, few interventions have been proven to prolong pregnancy in women at risk such as cervicovaginal fetal fibronectin (fFN) level or transvaginal cervical length measurements. In a meta-analysis comparing fetal breathing with cervicovaginal fetal fibronectin (fFN) level or transvaginal cervical length measurements, absence of fetal breathing was superior to other methods for prediction of preterm birth in 48 hours or 7 days. In this study, the investigators hypothesized that if a fetus holds its breath in case of preterm birth, then there may be specific fetal breathing patterns during preterm labor, which may be detected by ultrasonography

Preterm birth refers to a delivery that occurs before 37 weeks of gestation and it is the leading cause of neonatal morbidity and mortality. 33% of prenatal hospital admissions are due to preterm labor but almost 50% of patients receiving tocolytics in order to prevent birth deliver in the term period. Therefore, identification of those who will eventually deliver in the preterm period is very important. Ideally, identification of modifiable and nonmodifiable risk factors for preterm birth in will lead to interventions that help prevent this complication. However, few interventions have been proven to prolong pregnancy in women at risk such as cervicovaginal fetal fibronectin (fFN) level or transvaginal cervical length measurements. Another method for preterm birth prediction is presence of fetal breathing. In a meta-analysis comparing fetal breathing with cervicovaginal fetal fibronectin (fFN) level or transvaginal cervical length measurements, absence of fetal breathing was superior to other methods for prediction of preterm birth in 48 hours or 7 days. In this study, the investigators hypothesized that if a fetus holds its breath in case of preterm birth, then there may be specific fetal breathing patterns during preterm labor, which may be detected by ultrasonography

Inclusion Criteria:

• Pregnant patients between 24-37 gestational weeks with preterm labor : Uterine contractions ≥4 in number in 20 minutes or ≥ 8 in number in 60 minutes and one of the following:
• Cervical dilation ≥ 3 cm
• Transvaginal cervical length <20mm

Exclusion Criteria:

• Multifetal pregnancy
• Cervical dilation > 5 cm
• Heavy vaginal bleeding
• Non-reassuring fetal non-stress test
• Preterm premature rupture of membranes
• Intrauterine growth restriction
• Oligohydramniosis
• Fetal anomaly
• Patients who received tocolytics for preterm labor or corticosteroids for lung maturation
• Drug or substance use which may depress fetal breathing