Is pulmonary embolism in an infant fatal?

Can be: A pulmonary embolism, regardless of the age of the patient, can be fatal. It should be noted that not all pulmonary emboli are fatal and the incidence of pulmonary emboli in infants is quite small.

Yes, but rare: It can be, but its rare except at or near birth.

Possible: Pulmonary embolism can be fatal at any age, and should be treated immediately.

Not necessarily: Pulmonary embolism is unfortunately a relatively common cause of death, but with emergent treatment it is most frequently treatable.

Can Be; Not Always: A pulmonary embolus is serious and can certainly be fatal. But an infant can survive smaller emboli. Survival depends on the size and other conditions of the child.