Persistent fetal circulation is a medical condition where the blood circulation of a newborn baby does not change after birth, causing inadequate oxygen delivery to various organs. There are several synonyms for the term persistent fetal circulation, including persistent pulmonary hypertension of the newborn (PPHN), neonatal pulmonary hypertension, or persistent neonatal circulation. All these terms describe the same phenomenon where lung blood vessels fail to relax shortly after birth, leading to high blood pressure in the lungs and reduced oxygen levels in the body. PPHN is a critical condition that requires immediate medical attention and treatment, and it can lead to long-term health complications if left untreated.