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Limits of viability: definition of the gray zone

Journal of Perinatology volume 28, pages S4–S8 (2008)Cite this article

Abstract

Introduction:

As survival and long-term morbidity of very preterm infants have improved over the past decade, the limits of infant viability, the level of maturity below which survival and/or acceptable neurodevelopmental outcome are extremely unlikely, have also decreased.

Study Design:

In an effort to define the current limits of infant viability, the data in the literature on survival and long-term neurodevelopmental outcome in very preterm neonates have been reviewed.

Result:

The gestational age and birth weight below which infants are too immature to survive, and thus provision of intensive care is unreasonable, appears to be at <23 weeks and <500 g, respectively. Infants born at ⩾25 weeks' gestation and with a birth weight of ⩾600 g are mature enough to warrant initiation of intensive care, as the majority of these patients survive, and at least 50% do so without severe long-term disabilities. Finally, for infants born between 230/7 and 246/7 weeks' gestation and with a birth weight of 500 to 599 g, survival and outcome are extremely uncertain. For these infants born in the so-called ‘gray zone’ of infant viability, the line between patient autonomy and medical futility is blurred, and medical decision-making becomes even more complex and needs to embrace careful consideration of several factors. These factors include appraisal of prenatal data and the information obtained during consultations with the parents before delivery; evaluation of the patient's gestational age, birth weight and clinical condition upon delivery; ongoing reassessment of the patient's response to resuscitation and intensive care and continued involvement of the parents in the decision-making process after delivery.

Conclusion:

Based on these findings an algorithm is offered for consideration for neonatologists managing infants born in the ‘gray zone’ of infant viability. However, caution must be exercised when one considers incorporating this guideline into clinical practice because the algorithm is based on the analysis of the findings in the literature and the authors' experience rather than direct evidence.

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Author information

Authors and Affiliations

  1. Center for Fetal and Neonatal Medicine and the USC Division of Neonatal Medicine, Department of Pediatrics, Childrens Hospital Los Angeles and Women's and Children's Hospital of the LAC+USC Medical Center, Keck School of Medicine, University of California, Los Angeles, CA, USA

    I Seri

  2. Division of Neonatology, Department of Medicine, The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA

    J Evans

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  1. I Seri
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  2. J Evans
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Correspondence to I Seri.

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Disclosure

This paper was supported by a grant from Dey, L.P. Dr. Seri is on the scientific advisory board for Dey, L.P. Dr. Evans has received consulting fees from Discovery Labs and lecture fees from NO Therapeutics.

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Seri, I., Evans, J. Limits of viability: definition of the gray zone. J Perinatol 28 (Suppl 1), S4–S8 (2008). https://doi.org/10.1038/jp.2008.42

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  • DOI: https://doi.org/10.1038/jp.2008.42

Keywords

  • neurodevelopmental outcome
  • grayzone
  • qualitative benefit
  • infant viability
  • evidence- and nonevidence-based algorithm

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