Background and Aim: The need for more fetal echocardiography by a specialist in isolated single umbilical artery (SUA) pregnancies is controversial. Therefore, this study aimed to investigate the frequency of SUA in fetal ultrasound in neonates with congenital heart disease (CHD) compared to neonates without CHD referred to Hazrat Masoumeh Hospital in 2019. Materials and Methods: The files of all the neonates who underwent fetal ultrasound and echocardiography in 2019 were reviewed. Based on the results of the fetal echocardiography, these neonates were divided into two groups with/without cardiac abnormalities. Then, the results of fetal ultrasound performed in terms of the frequency of SUA were examined in the groups, and variables, such as birth, weight, gestational age, and gender were entered into the checklist. Finally, the frequency of SUA in fetuses with/without cardiac abnormalities was compared between the two groups. Results: The mean age of mothers in the SUA group was 32.47±8.7 years and in the normal group was 32.07±11.5 years. A total of 135 boys (54%) and 115 girls (46%) were examined in this study. No statistically significant relationship was found between maternal age (P=0.72), fetal gender (P=0.92), gestational age (P=0.42), and parity (P=0.92) despite the finding of a SUA. In the group of patients with CHD, 12 out of 125 patients (4.8%), and in the group without CHD, five out of 125 patients (2%) had an SUA. Although this number was highest in the group who had CHD, no statistically significant difference was found between the two groups (0.07). Conclusion: The relationship between SUA in a fetus with normal ultrasound and CHD varies significantly with population selection criteria. The risk of CHD after diagnosing SUA in a normal fetus from an unselected population appears to be low and may not warrant specialized fetal echocardiography.