What could cause a pulse oximetry reading of less than 90% in a newborn?

• A. Poor feeding
• B. Congenital heart disease
• C. Mild respiratory distress
• D. Normal physiological variation

Answer: (B)

A pulse oximetry reading of less than 90% in a newborn is particularly concerning and could indicate significant underlying issues, with congenital heart disease being one of the most critical causes. Congenital heart disease can lead to inadequate oxygenation of blood, as structural defects may compromise normal blood flow and oxygen delivery throughout the body. When the heart's function is impaired due to these structural anomalies, it can manifest as decreased oxygen saturation levels measured by pulse oximetry.

While other factors, like mild respiratory distress or poor feeding, can certainly influence blood oxygen levels, they are less likely to cause such a dramatic drop in saturation levels, especially below 90%. Normal physiological variation is expected in some newborns but does not typically lead to low oxygen saturation readings as severe as those seen with congenital heart issues. Therefore, it's critical to investigate cases of low pulse oximetry readings further, particularly for the potential of congenital heart disease. Early diagnosis and intervention in these cases can significantly affect outcomes for the newborn.