Critical congenital heart diseases are life-threatening, with a high morbidity rate and mortality among newborns; in fact, a newborn discharged from the hospital with undiagnosed heart disease may experience severe complications during the initial days or weeks of their life, necessitating emergency care and even death. Among all kinds of critical congenital heart disease, coarctation of the aorta is one of the most difficult to diagnose because it only becomes noticeable a few days after birth, when patients have already been discharged from the hospital. This underlines the importance of having a reliable diagnostic tool to discover these diseases. The identification of some of these patients can be achieved through newborn screening with pulse oximetry, but only a small number are diagnosed. Hence, the objective of this review was to determine the value of pulse oximetry screening for the early detection of congenital heart defects in newborns, with a focus on coarctation of the aorta. A literature search was conducted between December 2023 and February 2024 using four electronic databases: Pubmed, Google Scholar, Embase, and Scopus to identify studies that evaluated the efficacy of pre- and post-discharge neonatal ductal saturation monitoring for the diagnosis of critical congenital heart defects before discharge. Twenty research studies with a large number of patients, demonstrating moderate sensitivity and high specificity of pulse oximetry test in detecting critical heart defects, especially coarctation of the aorta, were selected and analyzed. Many confirmations have been found of how good the specificity of screening is, reaching an average value of 99.9% in each study analyzed. The problem still lies in the sensitivity of the screening, which is not as good as the specificity, never reaching 90% in any of the studies analysed. So, it is crucial to keep up with efforts to improve the efficacy of the pulse oximetry screening method.