What factor is likely causing symptoms in a newborn with a mother who experienced prolonged rupture of membranes?

In the context of a newborn whose mother experienced prolonged rupture of membranes, the most likely cause of symptoms is sepsis. Prolonged rupture of membranes, defined as more than 18 to 24 hours, significantly increases the risk of infection for both the mother and the newborn. When the membranes rupture, the protective barrier against bacteria is lost, making it easier for organisms from the maternal genital tract to ascend and potentially infect the amniotic fluid and the infant.

Infection can lead to sepsis in the newborn, characterized by symptoms such as temperature instability, respiratory distress, and feeding difficulties. Early-onset sepsis (which occurs within the first 72 hours after birth) is particularly a concern in these situations. Monitoring for signs of infection in newborns with a history of prolonged rupture of membranes is critical for timely diagnosis and intervention.

While congenital heart disease, hypoglycemia, and transient tachypnea of the newborn may also present with symptoms in newborns, they do not have the same direct and immediate association with prolonged rupture of membranes as sepsis does. These conditions can occur for various reasons unrelated to the status of the membranes during labor or delivery. Thus, sepsis is the most pertinent factor to consider in this clinical scenario.