Official reprint from UpToDate®
www.uptodate.com ©2017 UpToDate, Inc. and/or its affiliates. All Rights Reserved.

Periviable birth (Limit of viability)

Richard A Ehrenkranz, MD, FAAP
Mark R Mercurio, MD, MA
Section Editor
Richard Martin, MD
Deputy Editor
Melanie S Kim, MD


Periviability, also referred to as the limit of viability, is defined as the stage of fetal maturity that ensures a reasonable chance of extrauterine survival. With active intervention, most infants born at 26 weeks and above have a high likelihood of survival, and virtually none below 22 weeks will survive. The chance of survival thus increases dramatically over these few weeks, and this crucial time window may be considered the period of periviability. In addition to the high risk of death in the immediate newborn period, children born at the limit of viability have a high risk of permanent disability. An understanding of both of these risks is essential to parental counseling and decision-making, with regard to attempted resuscitation and provision of life-sustaining measures in the newborn intensive care unit (NICU).

Survival and morbidity of extremely preterm infants born below 26 weeks gestation will be reviewed. In addition, a management approach for infants born in the periviable period, based upon prognosis, will be presented. The management of pregnancies at or near the limit of viability is discussed separately. (See "Delivery of the preterm low birth weight singleton fetus", section on 'Management at the limit of viability'.)


Factors that affect survival rates in extremely preterm infants (gestational age [GA] <26 weeks) include GA, birth weight (BW), gender, plurality, and the use of antenatal corticosteroid therapy [1-3].

Gestational age — The major factor in determining viability is GA. Survival rates reported in a number studies [1,4-18] during the initial neonatal intensive care unit (NICU) admission for infants 22 to 25 completed weeks gestation (220/7 to 256/7 weeks gestation) are displayed in the table (table 1). These reports span time periods ranging from six months to six years between 1993 and 2014, and represent several large geographic areas in Western Europe, Japan, a network of tertiary level academic centers in the United States, and a population-based study of California. These data clearly demonstrated the rise of survival rate as GA increased from 22 to 25 weeks, as well as improvement in survival of periviable infants over the past two decades.

These publications and the changes in outcome emphasize the importance of basing discussions about delivery room management for periviable infants upon the latest available data. In addition, although these results highlight the impact of GA on viability, it is important to recognize that ascertaining an accurate GA is challenging. Thus, estimated GA alone may not truly reflect the prognosis. (See 'Interpreting the data' below and "Postnatal assessment of gestational age" and "Prenatal assessment of gestational age, date of delivery, and fetal weight".)

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:

Subscribers log in here

Literature review current through: Nov 2017. | This topic last updated: Oct 31, 2017.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2017 UpToDate, Inc.
  1. Tyson JE, Parikh NA, Langer J, et al. Intensive care for extreme prematurity--moving beyond gestational age. N Engl J Med 2008; 358:1672.
  2. Modi N. Survival after extremely preterm birth. BMJ 2008; 336:1199.
  3. Bader D, Kugelman A, Boyko V, et al. Risk factors and estimation tool for death among extremely premature infants: a national study. Pediatrics 2010; 125:696.
  4. Field DJ, Dorling JS, Manktelow BN, Draper ES. Survival of extremely premature babies in a geographically defined population: prospective cohort study of 1994-9 compared with 2000-5. BMJ 2008; 336:1221.
  5. Costeloe K, Hennessy E, Gibson AT, et al. The EPICure study: outcomes to discharge from hospital for infants born at the threshold of viability. Pediatrics 2000; 106:659.
  6. Larroque B, Bréart G, Kaminski M, et al. Survival of very preterm infants: Epipage, a population based cohort study. Arch Dis Child Fetal Neonatal Ed 2004; 89:F139.
  7. Markestad T, Kaaresen PI, Rønnestad A, et al. Early death, morbidity, and need of treatment among extremely premature infants. Pediatrics 2005; 115:1289.
  8. Itabashi K, Horiuchi T, Kusuda S, et al. Mortality rates for extremely low birth weight infants born in Japan in 2005. Pediatrics 2009; 123:445.
  9. EXPRESS Group, Fellman V, Hellström-Westas L, et al. One-year survival of extremely preterm infants after active perinatal care in Sweden. JAMA 2009; 301:2225.
  10. Stoll BJ, Hansen NI, Bell EF, et al. Neonatal outcomes of extremely preterm infants from the NICHD Neonatal Research Network. Pediatrics 2010; 126:443.
  11. Seaton SE, King S, Manktelow BN, et al. Babies born at the threshold of viability: changes in survival and workload over 20 years. Arch Dis Child Fetal Neonatal Ed 2013; 98:F15.
  12. Ishii N, Kono Y, Yonemoto N, et al. Outcomes of infants born at 22 and 23 weeks' gestation. Pediatrics 2013; 132:62.
  13. Carlo WA, McDonald SA, Fanaroff AA, et al. Association of antenatal corticosteroids with mortality and neurodevelopmental outcomes among infants born at 22 to 25 weeks' gestation. JAMA 2011; 306:2348.
  14. Vanhaesebrouck P, Allegaert K, Bottu J, et al. The EPIBEL study: outcomes to discharge from hospital for extremely preterm infants in Belgium. Pediatrics 2004; 114:663.
  15. Ancel PY, Goffinet F, EPIPAGE-2 Writing Group, et al. Survival and morbidity of preterm children born at 22 through 34 weeks' gestation in France in 2011: results of the EPIPAGE-2 cohort study. JAMA Pediatr 2015; 169:230.
  16. Stoll BJ, Hansen NI, Bell EF, et al. Trends in Care Practices, Morbidity, and Mortality of Extremely Preterm Neonates, 1993-2012. JAMA 2015; 314:1039.
  17. Anderson JG, Baer RJ, Partridge JC, et al. Survival and Major Morbidity of Extremely Preterm Infants: A Population-Based Study. Pediatrics 2016; 138.
  18. Stensvold HJ, Klingenberg C, Stoen R, et al. Neonatal Morbidity and 1-Year Survival of Extremely Preterm Infants. Pediatrics 2017; 139.
  19. Lamberska T, Luksova M, Smisek J, et al. Premature infants born at <25 weeks of gestation may be compromised by currently recommended resuscitation techniques. Acta Paediatr 2016; 105:e142.
  20. Kugelman A, Bader D, Lerner-Geva L, et al. Poor outcomes at discharge among extremely premature infants: a national population-based study. Arch Pediatr Adolesc Med 2012; 166:543.
  21. Inoue H, Ochiai M, Yasuoka K, et al. Early Mortality and Morbidity in Infants with Birth Weight of 500 Grams or Less in Japan. J Pediatr 2017; 190:112.
  22. Manktelow BN, Seaton SE, Field DJ, Draper ES. Population-based estimates of in-unit survival for very preterm infants. Pediatrics 2013; 131:e425.
  23. Bodeau-Livinec F, Marlow N, Ancel PY, et al. Impact of intensive care practices on short-term and long-term outcomes for extremely preterm infants: comparison between the British Isles and France. Pediatrics 2008; 122:e1014.
  24. Moore GP, Lemyre B, Barrowman N, Daboval T. Neurodevelopmental outcomes at 4 to 8 years of children born at 22 to 25 weeks' gestational age: a meta-analysis. JAMA Pediatr 2013; 167:967.
  25. Younge N, Goldstein RF, Bann CM, et al. Survival and Neurodevelopmental Outcomes among Periviable Infants. N Engl J Med 2017; 376:617.
  26. Guinsburg R, Branco de Almeida MF, Dos Santos Rodrigues Sadeck L, et al. Proactive management of extreme prematurity: disagreement between obstetricians and neonatologists. J Perinatol 2012; 32:913.
  27. Raju TN, Mercer BM, Burchfield DJ, Joseph GF Jr. Periviable birth: executive summary of a joint workshop by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Academy of Pediatrics, and American College of Obstetricians and Gynecologists. Am J Obstet Gynecol 2014; 210:406.
  28. Tucker Edmonds B, McKenzie F, Farrow V, et al. A national survey of obstetricians' attitudes toward and practice of periviable intervention. J Perinatol 2015; 35:338.
  29. American College of Obstetricians and Gynecologists, Society for Maternal-Fetal Medicine. Obstetric Care consensus No. 6: Periviable Birth. Obstet Gynecol 2017; 130:e187.
  30. Donovan EF, Tyson JE, Ehrenkranz RA, et al. Inaccuracy of Ballard scores before 28 weeks' gestation. National Institute of Child Health and Human Development Neonatal Research Network. J Pediatr 1999; 135:147.
  31. Mercurio MR. The ethics of newborn resuscitation. Semin Perinatol 2009; 33:354.
  32. Marlow N. Interpreting regional differences in neonatal outcomes for extremely preterm babies. Acta Paediatr 2014; 103:4.
  33. Serenius F, Sjörs G, Blennow M, et al. EXPRESS study shows significant regional differences in 1-year outcome of extremely preterm infants in Sweden. Acta Paediatr 2014; 103:27.
  34. Rysavy MA, Li L, Bell EF, et al. Between-hospital variation in treatment and outcomes in extremely preterm infants. N Engl J Med 2015; 372:1801.
  35. Mehler K, Oberthuer A, Keller T, et al. Survival Among Infants Born at 22 or 23 Weeks' Gestation Following Active Prenatal and Postnatal Care. JAMA Pediatr 2016; 170:671.
  36. Serenius F, Blennow M, Maršál K, et al. Intensity of perinatal care for extremely preterm infants: outcomes at 2.5 years. Pediatrics 2015; 135:e1163.
  37. Perlbarg J, Ancel PY, Khoshnood B, et al. Delivery room management of extremely preterm infants: the EPIPAGE-2 study. Arch Dis Child Fetal Neonatal Ed 2016; 101:F384.
  38. Smith PB, Ambalavanan N, Li L, et al. Approach to infants born at 22 to 24 weeks' gestation: relationship to outcomes of more-mature infants. Pediatrics 2012; 129:e1508.
  39. Roberts G, Anderson PJ, Doyle LW, Victorian Infant Collaborative Study Group. The stability of the diagnosis of developmental disability between ages 2 and 8 in a geographic cohort of very preterm children born in 1997. Arch Dis Child 2010; 95:786.
  40. Hack M, Taylor HG, Drotar D, et al. Poor predictive validity of the Bayley Scales of Infant Development for cognitive function of extremely low birth weight children at school age. Pediatrics 2005; 116:333.
  41. Marlow N, Wolke D, Bracewell MA, et al. Neurologic and developmental disability at six years of age after extremely preterm birth. N Engl J Med 2005; 352:9.
  42. Mercurio MR. Physicians' refusal to resuscitate at borderline gestational age. J Perinatol 2005; 25:685.
  43. Mercurio MR. Parental authority, patient's best interest and refusal of resuscitation at borderline gestational age. J Perinatol 2006; 26:452.
  44. Wellesley H, Jenkins IA. Withholding and withdrawing life-sustaining treatment in children. Paediatr Anaesth 2009; 19:972.
  45. D'Angio CT, Mercurio MR. Evidence-based ethics in the 'gray zone' of neonatal viability: promises and limitations. Pediatr Health 2008; 2:777.
  46. American Heart Association and American Academy of Pediatrics. Neonatal Resuscitation, 7th, Weiner G (Ed), American Academy of Pediatrics, Elk Grove Village 2016. p.262.
  47. American Heart Association and American Academy of Pediatrics. Neonatal Resuscitation, 6th ed, Kattwinkel J (Ed), American Academy of Pediatrics, Elk Grove Village 2011. p.5.
  48. Cummings J, COMMITTEE ON FETUS AND NEWBORN. Antenatal Counseling Regarding Resuscitation and Intensive Care Before 25 Weeks of Gestation. Pediatrics 2015; 136:588.
  49. Nuffield Council on Bioethics. Guidelines on giving intensive care to premature babies. 2006. http://www.nuffieldbioethics.org/neonatal-medicine/neonatal-medicine-background-extremely-premature-babies (Accessed on February 07, 2011).
  50. Guillén Ú, Weiss EM, Munson D, et al. Guidelines for the Management of Extremely Premature Deliveries: A Systematic Review. Pediatrics 2015; 136:343.
  51. Fanaroff JM, Hascoët JM, Hansen TW, et al. The ethics and practice of neonatal resuscitation at the limits of viability: an international perspective. Acta Paediatr 2014; 103:701.