Centile charts of cervical length in singleton and twin pregnancies between 16 and 24 weeks of gestation

OBJECTIVE: The aim of this study was to determine the standard mid-trimester cervical lengths of singleton and twin pregnancies. MATERIAL AND METHODS: This study was conducted by retrospective analysis of mid-trimester transvaginal cervical measurements of women with singleton and twin pregnancies that were examined by a single perinatologist in a single center. RESULTS: A total of 4621 consecutive asymptomatic pregnant women admitting for advanced obstetric ultrasound screening were evaluated. Of these 4340 (93.9%) were second trimester singleton pregnancies and 281 (6.1%) were twin pregnancies and were included. Mean cervical length measurements of singleton and twin pregnancies were 38.2±6.5 mm and 37.6±7.2 mm respectively (p=0.17). Overall, the 5(th) percentile of cervical length measurement after analysing singleton and twin pregnancies together was 29.4 mm at 16 weeks, 30 mm at 17 weeks, 30 mm at 18 weeks, 30 mm at 19 weeks, 30 mm at 20 weeks, 30 mm at 21 weeks, 30 mm at 22 weeks, 31 mm at 23 weeks, 29 mm at 24 weeks. CONCLUSION: In our population the 5(th) precentile value of cervical length which is 30 mm in singletons and 10(th) percentile cervical length which is 31 mm in twins can be used to follow-up and treat pregnant women at risk for preterm delivers.