Critical congenital heart disease (CCHD) defined as congenital heart disease (CHD) requiring surgery or catheter-based intervention in the first year of life. Congenital heart disease (CHD) itself is the most common congenital disorder found in newborns. Prevalence of CHD at birth ranges from 8 to 10 per 1000 live births. CCHD occurs in approximately 25 percent of those with CHD. Although many newborns with CCHD are symptomatic and identified soon after birth, others are not diagnosed until after discharge from the birth hospitalization. The risk of morbidity and mortality increases when there is a delay in diagnosis and timely referral to a tertiary center in treating those patients. CCHD includes ductal-dependent and cyanotic lesions CHD that are may not require surgery in the neonatal period but still require intervention in the first year of life. Early detection of CCHD help us to provide a prompt treatment. Early detection includes the clinical suspicion of a risk factor for CHD by clinicians so that the referral for fetal echocardiography can be done. Prenatal detection has become a significant contributor to early identification of CCHD. A recent meta-analysis has shown that newborns with a prenatal diagnosis of CCHD were significantly less likely to die before planned cardiac surgery than those with a comparable postnatal diagnosis. Even with fetal echocardiograms, which are not available universally, the diagnosis of CCHD during pregnancy is difficult. A thorough physical examination should be performed with attention to findings suggestive signs of CHD, including abnormal precordial activity, abnormal heart sounds, pathologic murmurs, hepatomegaly, diminished or absent lower extremity pulses, abnormal four extremity blood pressure, shock, cyanosis, and respiratory symptoms. A pulse oximeter can help the nursery clinicians identify babies who have oxygen saturation levels below 95% (