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Time of Collection

Full term infants

  • A newborn screening sample should be collected between 24 and 48 hours of age.

Infants discharged early (less than 24 hours of age)

  • A newborn screening sample should be collected between 24 and 48 hours of age. If an infant is discharged before 24 hours of age:
    • Inform parents/guardians that a repeat newborn screen must be done after 24 hours and explain how this can be arranged. If possible, a repeat should be collected within the routine timeframe for specimen collection (i.e. 24-48 hours of age), or within 5 days of the initial sample.
  • Not all diseases are reliably detected using blood samples taken before 24 hours of age. Samples obtained at less than 24 hours of age are considered unsatisfactory and a repeat sample will be requested.
    • Specimens collected at less than 24 hours of age, while unsatisfactory, are still analyzed by NSO. If the results are “screen positive” for any disease NSO will initiate appropriate follow-up. A repeat newborn screen is required to complete newborn screening for the infant.
  • The health care provider who submitted the initial sample is responsible for ensuring a repeat sample is collected. NSO recommends that each submitter develop a process to obtain repeat samples for these infants. All correspondence with parents/guardians and/or primary health care providers surrounding the collection of repeat specimens should be documented in the infant’s medical record.


  • Provide parents/guardians with a follow-up appointment at the time of discharge to obtain a repeat sample if the initial sample was obtained at less than 24 hours of age.
  • Maintain a log of infants that require a repeat newborn screen to help ensure repeat samples are collected and facilitate communication with NSO.

Infants transferred to another facility

A newborn screening sample should be taken prior to discharge from the birth hospital. If transfer occurs less than 24 hours of age or a newborn screening sample was not taken at the birth hospital, this information should be included in the discharge summary and the receiving hospital should collect the newborn screening sample. Clear communication between the two hospitals involved is essential to ensure the newborn screen is taken.

Samples collected from infants greater than 7 days of age

Samples taken from infants who are greater than 7 days of age are analyzed.

As the levels of many screening markers drop over the first week of life, these lab results are checked manually to minimize the risk of missing an affected child (false negative results).

Contact NSO

Subscribe to the Submitter Bulletins to stay up to date on the latest newborn screening updates, or submit a question about newborn screening.

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