The world health organisation (WHO) defines preterm birth as babies born at less than 37 weeks of a 40 week term (1). Preterm birth is further categorised on the basis of advancing weeks of prematurity from 22 weeks (2).
Degree of prematurity
Age range (weeks)
Birth Weight (g)
% Survival (live births)
32 - 37
28 - <32
26 - <28
22 - 25
Borderline of viability
Table 1. Defined categories of preterm birth are based on the stage of development in weeks.
Babies born much earlier than this, at less than 25 weeks are described as existing at the ”border of viability”. The period between 22 and 25 weeks is often referred to as the “grey zone” (3). Although these babies are healthy in the womb, they often die when they are born so extremely early because their lungs, heart, brain and kidneys are too immature to cope outside the womb. These babies fall through the cracks when it comes to active healthcare and many hospitals are unable treat them because of their extreme prematurity. Babies born between 22-25 weeks are the focus of this organisation.
The scale of the problem
The scale of the problem is concerning with an estimated 270,000 infants born extremely preterm between 22 to 25 weeks across the developed world each year, (4, 5). The total numbers across underdeveloped countries are unknown given the difficulty of obtaining comparable or reliable data (6). However, a conservative estimate of half a million infants born between 22 -25 weeks, makes this a truly global problem. An estimated 70% of these infants do not survive to leave hospital, and those that do, endure months or years of rehabilitation as the result of prematurity related complications and childhood illness. In addition, of those that leave hospital, many are still at risk of death before the age of 5. Compared to babies born after 28 weeks, those born less than 25 weeks are especially vulnerable to prematurity related health conditions including, blindness, learning impairment, cerebral palsy, lung damage, heart disease, brain injury and delays in growth, (7).
Table 2. Estimated numbers of infants born at the border of viability in developed and developing regions each year, based on the percentage of live births in Australia. Rate of extremely preterm births based on 0.34% of total births in New South Wales and the Australian Capital Territory.
What are the costs of extreme preterm birth?
The emotional toll on parents watching their little ones suffer in hospital with no end in sight cannot be overstated. The lucky few that make it home undergo ongoing treatment that in many cases leads to significant financial burden to families. Chronic ill health means lost income for many individuals or the inability to work, (8, 9).
The financial cost to raise a child with special needs to the age of 18 is estimated at $2.5 million compared to an individual born without impairment. This means that Australia may spend approximately $750 million per year with much of this cost being absorbed by families and Government funded facilities, including education, healthcare and social support.
The time has come for a new way forward for the tens of thousands of infants born extremely preterm, less than 25 weeks. You can make a difference right now by helping to fund research that will give these infants a precious beginning.
1. http://www.who.int/topics/preterm_birth/en/ 2. Preterm birth. Fact Sheet No 363. World Health Organization. http://www.who.int/mediacentre/factsheets/fs363/en/ 3. Seri, I. Evans, J. Limits of viability: definition of the gray zone. Journal of Perinatology (2008) 28, S4-S8. 4. Keogh J. Aus NZ J Obstet Gynaecol. 2007. 5. Tracy SK. Brit J Obstet Gynaecol. 2007. 6. Beck, S. The worldwide incidence of preterm birth: a systematic review of maternal mortality and morbidity. Bulletin of the World Health Organization 2010;88:31-38. 7. Wood N. S. The EPICure study: growth and associated problems in children born at 25 weeks of gestational age or less. Arch. Dis. Child Fetal Neonatal Ed. 2003; 88: F492-F500. 8. Gilbert W. M. The cost of preterm birth: the low cost versus high value of tocolysis. BJOG 2006; 113 (Suppl. 3): 4-9. 9. Russell, R. Cost of hospitalization for preterm and low birth weight infants in the United States. Pediatrics 2007;1 120; e1-e9.