Professor of Pediatrics
University of Iowa Stead Family Children’s Hospital, USA
Dr. Bell received his M.D. from Columbia University. He completed residency in pediatrics at Columbia University and fellowships in neonatology at McMaster University and Brown University. He is Professor of Pediatrics at the University of Iowa. He was Director of Neonatology at the University of Iowa from 1988 until 2005 and, since then, has served as Vice Chair for Faculty Development in the Department of Pediatrics. Throughout his career, he has conducted clinical and translational research related to the care of prematurely born infants. He is principal investigator of the University of Iowa center in the NICHD Neonatal Research Network. Dr. Bell and his colleagues at the University of Iowa have been leaders in the management of infants at the limit of viability, and their outcomes for infants born at 22 and 23 weeks of gestation are among the best in the world. He developed and maintains The Tiniest Babies Registry, a web-based registry of surviving infants who weighed less than 400 grams at birth. Dr. Bell presented at the 2009 REaSoN conference.
Care of the 22-week infant – no longer futile
The gestational age at which intact survival is possible for significant numbers of infants has moved earlier over time and is now at 22 weeks. This marker is often called the limit of viability. However, defining viability based simply on gestational age is overly simplistic, as the chance of survival depends on other factors besides gestational age, in particular sex, birth weight, plurality, exposure to antenatal glucocorticoids, and the hospital of birth. The interaction of these predictive factors is complex and is beyond the scope of this presentation but was the subject of a recent publication by Matthew Rysavy et al: “Assessment of an Updated Neonatal Research Network Extremely Preterm Birth Outcome Model in the Vermont Oxford Network,” JAMA Pediatrics 2020 Mar 2 [Epub ahead of print]. Please update citation when volume and page numbers available.
When discussing the survival of extremely preterm infants, it is important to state clearly the denominator, i.e. all liveborn infants or only actively treated infants, and the point at which survival is determined, i.e. survival to hospital discharge or survival to 1 or 2 years of age. The survival to hospital discharge of liveborn 22-week infants varies greatly among hospitals, and this variability can be explained largely by variation in the hospitals’ rates of active treatment of these infants. In recent years, the rates of both active treatment and survival for 22-week infants have increased in U.S. hospitals that participate in the Vermont Oxford Network.
Selected hospitals and national health systems in several countries are now reporting survival of 22-week infants above 50%, even when expressed as percent of liveborn infants. The limited data available on neurodevelopmental outcome of 22-week infants at 2-3 years of age indicate risks similar to 23 and 24-week infants. One-third to one-half have no or only minor neurodevelopmental impairment in several cohorts.