"早产儿保育器" can be translated as "premature infant incubator" or "neonatal incubator for preterm babies" in English.
"Premature infant incubator" directly refers to the device used for caring for premature infants.
"Neonatal incubator for preterm babies" is a more descriptive phrase, specifying that the incubator is intended for preterm (早产) newborns (neonatal).
Both translations are accurate and commonly used in medical contexts.