Could a congenital diaphragmatic hernia be life-threatening for the infant?

Absolutely: If the abdominal contents come up through the hernia into the chest when the baby is born, they can prevent the lungs from expanding properly and prevent the newborn from breathing effectively. If known ahead of time, baby should be delivered in a place that can do immediate surgery on infant. Some places even doing the surgery before baby born. You need a maternal-fetal specialist to help out.

Yes: Infant would need to be born at hospital with level three intensive care nursery and access to pediatric surgery, pediatric cardiology.

Lethal if severe..: Cdh is always serious, frequently life-threatening and sometimes perinatally lethal even with optimal care. In fact, it is frequently lethal if severe, untreated, unsuspected prenatally, or substandardly treated in utero or postnatally. See dr. Rodrigo ruano at tch pavilion for women in houston, tx, for endotracheal balloon occlusion fetal therapy to optimize outcomes of severe cases.