Which condition is primarily responsible for persistent pulmonary hypertension in neonates?

Persistent pulmonary hypertension in neonates is primarily associated with hypoxemia. In a healthy newborn, the circulatory system undergoes significant changes at birth, transitioning from reliance on the placenta to independent breathing and oxygenation of the lungs. If a neonate experiences low oxygen levels, or hypoxemia, this can lead to a failure of the normal circulatory adjustments, resulting in elevated pulmonary arterial pressure.

When the lungs are not adequately oxygenated, pulmonary vasoconstriction occurs, which increases pressure in the pulmonary arteries. This persistent high pressure is what characterizes pulmonary hypertension. Hypoxemia can stem from various underlying conditions, including meconium aspiration, congenital heart defects, or lung diseases, but the common pathway that exacerbates the condition is the inadequate oxygenation of blood.

In contrast, while cystic fibrosis, maternal hypertension, and respiratory distress syndrome can affect neonates and may lead to complications, they are not the primary condition linked to persistent pulmonary hypertension. Cystic fibrosis usually presents later in life and is more related to issues of mucus buildup rather than immediate pulmonary hypertension. Maternal hypertension may adversely affect fetal health, but hypoxemia following birth has a more direct impact on pulmonary vascular resistance. Respiratory distress syndrome is primarily characterized by