As a result of low oxygen levels, infants with PPHN are at an increased risk of developing complications, such as asphyxia, chronic lung disease, neurodevelopment issues, and death.Nosocomial infections are another type of complication that may contribute to mortality in someone with PPHN. If the newborn acquires an infection while hospitalized, this could result in deterioration of the condition even after days of improvement. Pathophysiology
Typically, a fetus experiences pulmonary hypertension in utero since it is relying on the placenta for oxygen rather than its lungs. When the fetus is born, it is no longer attached to the placenta and must use the lungs to receive oxygen. To facilitate this change from fetus to newborn, the baby must change from a state of high PVR to low PVR, allowing for increased blood flow to circulate throughout the body. This inability of the newborn to adapt to these changes is caused by various processes, such as:

Normal vascular anatomy with functional vasoconstriction: This has a good prognosis, as it is reversible. Causes include hypoxia, meconium aspiration, and respiratory distress syndrome. Left untreated, this can lead to hypoxic respiratory failure (HRF). Decreased diameter of pulmonary vessels with hypertrophy of vessel walls: This has a poor prognosis, as it is a fixed abnormality. Causes include post-term pregnancy, placental insufficiency, and NSAID use by the mother. Decreased size of pulmonary vascular bed: This has a poor prognosis, as it is a fixed abnormality. It is caused by space occupying lesions such as pleural effusions and diaphragmatic hernias.
Treating this condition often involves large interdisciplinary teams, which is not always possible in developing countries. In low-resource environments, it is recommended to focus on five main bundles of management:
Increasing oxygen supply
Decreasing oxygen demand
Facilitating gas exchange
Inducing pulmonary vasodilation
Fixing metabolic disturbances

Epidemiology
It occurs in 1–2 infants per 1000 live births. It is more common in males and in areas with higher altitudes. Additionally, two percent of infants with respiratory distress syndrome develop PPHN. References
Further reading
Dunn PM (March 1994). "Professor Charles D Meigs (1792-1869) of Philadelphia and persistent fetal circulation". Archives of Disease in Childhood. Fetal and Neonatal Edition. 70 (2): F155-6. doi:10.1136/fn.70.2.f155. PMC 1061019. PMID 8154909. == External links ==