Objectives: To evaluate the diagnostic accuracy of TCD in prediction of gestational age and fetal weight in diabetic patients.
Subjects and methods: This prospective cross-sectional study was conducted on 84 pregnant women at third tri-mester of pregnancy who attended the antenatal care in the outpatient clinic at our hospital during the period from No-vember 2019 to  November 2021. Measurements of the TCD was performed and correlated with gestational age based on last normal menstrual period (LNMP)as well as estimated fetal weight. The study was approved by the Eth-ics Committee, and all patients gave their informed consent before inclusion in the study.  
Results: The mean age± SD ratio of the study group was 29.45±6.16years. The study group included 84 consecutive diabetic pregnant women; 2 females with diabetes type A1 (2.4%), 28 females with diabetes type A2 (33.3%), 33 fe-males with diabetes type B (39.3%), and 21 females with di-abetes type C (25%)..The mean fetal TCD± SD ratio at 32-34 weeks was 40.17±2.95mm and at 37 weeks was 50.42±3.04 mm. we found that there is a statistically significant positive correlation between TCD and estimated fetal weight at 32-34 weeks (r= 0.294, p= 0.007) and at 37 weeks (r= 0.475, p < 0.001).TCD has 94.1% accuracy in detection of the actual gestational age at 32-34 weeks and 95.2% accuracy in detec-tion of the actual gestational age at 37 weeks.
Conclusion: The current study has demonstrated that there is a statistically significant positive correlation between TCD and Estimated fetal weight at third trimester of pregnancy. TCD can be used as an accurate reliable method for the as-sessment of gestational age in third trimester. We recommend to conduct this study on larger sample size for further documentation of the proposed assumption.