Preterm birth is defined as birth before 37 completed week of gestation. To determine the diagnostic accuracy of cervical length measurement using transvaginal sonography in second trimester between 16-28 weeks of pregnancy as predictive value for spontaneous preterm labour in 80 asymptomatic women with singleton pregnancy. Maximum number of patients was in the age group between 20-29 years. Most of them were primigravidae or second gravidae.G3 and above comprise of 30% of patients. 6% of Cases were short cervix (<2.5 cm). 80% of short cervix patients delivered preterm. 5% of women with cervical length > 2.5 cm delivered Preterm and hence cervical length has a strong negative predictive value in ruling out preterm labour, in asymptomatic women. There was a greater incidence of perinatal morbidity in terms of NICU admissions, Preterm deliveries and birth asphyxia in patients with cervical length less than 2.5 cm as compared with those with normal cervical length.