Clinical and Laboratory Standards Institute guideline NBS03—Newborn Screening for Preterm, Low Birth Weight, and Sick Newborns describes newborn screening (NBS) of preterm, low birth weight (LBW), and sick newborns worldwide to detect treatable diseases before physical damage can occur. In developed countries, treatment advances have improved survival rates, making early disease detection by NBS even more important. The physiological states associated with preterm, LBW, and sick newborns and the treatments received directly affect the reliability of results for many diseases screened in public health by newborn dried blood spot screening, newborn hearing screening, and critical congenital heart disease (CCHD) screening. This guideline describes the effects of maternal and newborn conditions, as well as treatments given to newborns, that may affect NBS results. This guideline also provides the rationale for recommended screening intervals designed to minimize the risk of missing or delaying a diagnosis in an affected newborn. This guideline is intended for use by those involved in any aspect of NBS specimen collection, hearing screening, CCHD screening, and follow-up, including health care providers, public health professionals, and others concerned with newborn health and welfare.

This guideline replaces the previous edition of the approved guideline, NBS03-A, published in 2009. Several changes were made in this edition, including: 
• Condensed and combined tables to show the most relevant aspects for screening preterm, LBW, and sick newborns admitted to the SCBU/NICU 
• Added discussion of screening diseases organized by type (eg, endocrinopathies) focused specifically on implications of NBS for preterm, LBW, and sick newborns 
• Added new information covering the implications for this population of screening for diseases recently implemented in some NBS programs, such as SCID, LSDs, and point-of-care screening for CCHD 
• Added a description of alternative protocols and suggested elements to evaluate when different collection protocols and testing paradigms are considered, in addition to the recommended serial-screening protocol and algorithm

This guideline covers best practices for personnel in the SCBU/NICU and the NBS laboratory, primary health care providers (HCPs), and NBS program follow-up personnel, in order to provide all preterm, LBW, and sick newborns with valid newborn dried blood spot (DBS) screening and point-of-care (POC) screening. Best practices are established with consideration of special circumstances that may affect the recommended specimen collection timing and/or screening test result(s) interpretations. Special circumstances include the newborn’s condition and treatments administered, maternal conditions and therapies, and other factors affecting the optimal screening windows for the specific screened diseases in this population. This guideline focuses on treatments, practices, and newborn conditions seen in the SCBU/NICU that are either known or suspected to interfere with NBS test results, consequences of the interference, and recommendations for avoiding or counteracting these problems. 

This guideline is intended to provide guidance for ensuring rapid, consistent, and complete DBS and POC screening, including appropriate follow-up, to ensure early diagnosis and treatment for preterm, LBW, or sick newborns affected with a screened disease. If implemented, this guideline will assist NBS laboratories, NBS programs, and HCPs in: 
• Minimizing the risk of a missed or delayed diagnosis and treatment for all screened diseases 
• Minimizing the number of false-positive and/or false-negative NBS results in this population 
• Optimizing the timing and minimizing the number of DBS specimen collections 
• Optimizing the timing of and process for POC screening 
• Defining essential elements of QA relevant to this guideline 
• Providing education on the effects of SCBU and NICU treatments on newborn DBS screening 
• Supporting clinicians in optimizing use of NBS program functions for timely interventions 
• Identifying areas that need additional research This guideline is not intended to provide general information on screening for all diseases (only information pertinent to the SCBU/NICU population) or dictate SCBU/NICU care practices. 

This guideline does not include: 
• Discussion of data systems in SCBUs/NICUs that might facilitate implementing this guideline 
• Details of individual diseases screened, beyond salient points unique to the preterm, LBW, and sick newborn population 
• Recommendations about testing for X-linked adrenoleukodystrophy, because there is not yet sufficient experience with screening newborns, particularly the subpopulation of preterm, LBW, and sick newborns