Abstract     Accurate pregnancy dating helps obstetrician in appropriate counselling of women who present late in third trimester and may not keep the menstrual record properly and are at risk of preterm delivery. The present study was carried out to assess gestational age in second and third trimesters with the help of ultrasonic measurement of fetal parameters in local population of Uttar Pradesh and also to evaluate the efficacy of foetal biometric parameters in prediction of gestational age by ultrasound. A study was conducted on 100 pregnant females between 13 weeks and 38 weeks of gestation referred from antenatal clinics to department of Radio diagnosis in association with the department of Anatomy from 2015­2016. All singleton pregnant women aged between 15 and 35 years for routine antenatal ultrasound were included. Patient more than 35years with maternal diseases were excluded. These females were subjected to single exposure for estimation of mean gestational age using multiple foetal parameters. Then a comparison was made between menstrual gestational age and ultrasonic gestational age. The foetal parameters were also compared for accuracy and reliability with each other by linear regression. Biparital diameter and femur length were found to be best in predicting gestational age in second and third trimester. In this study 95% of cases had a difference of 2 weeks in second and third trimester. Hence, this study validates that multiple foetal parameters should be used to improve the accuracy and precision of foetal dating in both second and third trimester.

Keyword: Last Menstural Period, Ultrasonography, Foetal Parameters.