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Anticipated delivery and/or birth within the margin of viability, generally considered to be between 22 weeks 0 days and 25 weeks 6 days estimated gestational age.
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GUIDELINE OBJECTIVE(S)
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To address the following aspects of management of the fetus at the limits of viability. 1) Decrease variation in practice among individual clinicians providing antenatal counseling and/or delivery room care of infants born between 22 weeks 0 days and 25 weeks 6 days estimated gestational age. 2) Promote utilization of a shared decision-making strategy with the infant’s parents when providing antenatal counseling. 3) Describe how to appropriately use the ethical standard of “best interests” for an infant when making care plan decisions. 4) Define a “trial of therapy” and understand some of the limitations associated with this practice. 5) Understand how the law may influence decision-making about delivery room management of a periviable infant.
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Definition of Viability
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Human viability is most commonly defined as the time in fetal development when there is a reasonable likelihood of sustained survival of the fetus outside the womb, with or without artificial aid. Despite the relative simplicity of this definition, the practical concept of viability is actually quite complex. In reality, the point in time when viability occurs varies between individual pregnancies and is dependent on differences in fetal maturation rates as well as a multitude of other biologic and environmental factors (i.e., intrauterine growth restriction, presence of chorioamnionitis, and availability of antenatal steroid treatment). Furthermore, as medical innovation and technology have advanced over the past century, the definition of viability has evolved with it. Infants who would have not survived 50 years ago because of complications related to their prematurity are now not only surviving, but also thriving. This rapidly changing environment coupled with a “periviable” gray zone in which infants can be delivered has led to complex scientific, social, and ethical considerations.
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Survival of Periviable Infants
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In 2001, the National Institute for Child Health and Human Development (NICHD) Neonatal Research Network, which comprises 20 large academic centers across the United States, collected and published survival data for premature infants born weighing at least 500 g during the years 1995 and 1996. At that time, overall mortality was 100% for infants born at 21 weeks’ gestation, 79% for those at 22 weeks, 70% for those at 23 weeks, and 50% for those at 24 weeks. A decade later this data was reported again; however, due to shifts in resuscitation practices, the new report included all babies born with birth weights greater than 401 g. Despite the addition of smaller infants, the results were similar. The mortality rate for infants born at 22 weeks’ gestation was 94% with a reported range of 50% to 100% depending on the particular institution ...