What is the most likely cause of frothing at the mouth, cyanosis, and respiratory distress in a newborn with polyhydramnios?

The most likely cause of frothing at the mouth, cyanosis, and respiratory distress in a newborn with polyhydramnios is a deviation of the tracheoesophageal septum. This condition often leads to tracheoesophageal fistula (TEF), where an abnormal connection forms between the trachea and the esophagus. When this occurs, infants may present with respiratory distress due to aspiration of gastric contents into the lungs or inability to properly clear secretions.

The presence of polyhydramnios, which indicates excess amniotic fluid, can be a sign of fetal swallowing abnormalities, often associated with TEF. As the fetus is unable to swallow the amniotic fluid effectively due to the esophageal component being obstructed or malformed, this contributes to the excessive accumulation of fluid.

Frothing at the mouth occurs when secretions accumulate and overflow from the mouth, and cyanosis may result from impaired oxygenation, which can happen if the airway is compromised or if there is aspiration. The respiratory distress can stem from both obstruction and aspiration, leading to immediate concern for respiratory support.

The other conditions listed, while they can cause various symptoms in neonates, do not align as closely with the triad of frothing at the mouth