Final answer:
The optimal time for a neonatal screening test is between 24 to 72 hours after birth to allow for a newborn's metabolism to stabilize and ensure accurate detection of metabolic or genetic disorders.
Step-by-step explanation:
The optimal time to perform a neonatal screening test is between 24 to 72 hours after birth. This timeframe is recommended because it allows for the newborn's metabolism to stabilize, ensuring that the test can identify metabolic or genetic disorders such as phenylketonuria, hypothyroidism, cystic fibrosis, and sickle cell disease. Some conditions may not be detectable immediately after birth, which is why this window is optimal. Moreover, performing the test within this period allows for early detection and management of any potential health issues, improving the long-term outcome for the infant.