Sonographic evaluation of cervical length changes during normal pregnancy

This study was aimed to establish reference values of cervical length in normal pregnancy. We studied a cross-sectional sample of 144 pregnant women by transabdominal sonography. The inclusion criteria were sonographic confirmation of gestational age, the absence of any risk factors for preterm birth, and uncomplicated pregnancy. Cervical length was measured in a straight line. Height, age and weight of patients were also obtained. There was a relationship between gestational age and cervical length, which could be described with a linear regression (R = 0.44; P <0.05). Our study shows an increase in cervical length with gestational age. Reference ranges constructed for the whole gestational period could be more clinically applicable and useful than a single cut off value for more efficient prevention and management of preterm birth.