Introduction: Physiological changes that take place in uterus in early pregnancy play an important role in labour and delivery. The chances of preterm delivery and prolonged pregnancy are related to the length of the cervix measured during mid-pregnancy at around 20-24 weeks. There is a strong association between preterm delivery and short cervix. Similarly, long cervix in mid-pregnancy may be associated with risk of post dated pregnancy or caesarean section due to poor progress of labour among primigravidae. This study is based on the assumption that mid-pregnancy ultrasonographic measurement of cervical length can be a predictor of timing and mode of delivery. Aims and Objectives: 1) To determine the association between cervical length at mid-pregnancy and timing of delivery. 2) To determine the usefulness of mid-pregnancy ultrasonographic cervical length measurement in predicting mode of delivery. Materials and Methods: This study was done in primigravidae with singleton pregnancy with no comorbidities. Transvaginal sonography was done to measure the cervical length between 20-24 weeks of gestation. These patients were followed till delivery. Those who developed complications like GDM, GHTN, malpresentation or who required induction of labour before 40 weeks for other complications were excluded from the study. Measured cervical length was not revealed to the obstetrician conducting delivery. Timing of delivery whether preterm, term upto 40 weeks or post dated (after 40 weeks till 41+6 weeks) was observed. And also mode of delivery whether vaginal or caesarean section was observed and these results were correlated with mid trimester cervical length. Results: Totally 237 patients were studied, of which 173 satisfied inclusion criteria. Out of 15 patients with cervical length less than 3cms, 14(93.33%) had preterm delivery. Post dated pregnancy was observed in 46(92%) out of 50 patients with cervical length more than 4cms. In cervical length less than 3 cms group, 12 (80%) delivered vaginally. Among cervical length more than 4 cms group 24(48%) required caesarean section. Conclusion: It is concluded from the study that cervical length of less than 3cms measured between 20-24 weeks is associated with preterm births and favours vaginal birth. Whereas, cervical length of more than 4cms is associated with post dated pregnancy and increased risk of caesarean section.