Premature or preterm birth has many different considerations dependent on how early the degree of prematurity and associated clinical considerations for both the infant and mother. Initial content on this page is concerning very early birth period and not a discussion of infants born only slightly premature.
Premature Infant (Image CDC)
In very early births (22 - 25 weeks), the so-called "grey zone" of viability, there have been several recent recommendations and guidelines regarding clinical care being developed in different countries.
Page Links: Introduction | Some Recent Findings | Ethics | Preterm Birth Factors | Birth Weight | Preterm Labour | Preterm Trends | Australia Recommendations | United Kingdom Recommendations | USA Information | References | Glossary
Prevention of preterm birth: a renewed national priority Damus K. Curr Opin Obstet Gynecol. 2008 Dec;20(6):590-6.
"Noteworthy epidemiological changes in preterm births include a shift from 40 to 39 weeks as the most common length of gestation for singleton births in the United States; significant jumps in late preterm births, which is the major contributor to increasing preterm rates: more multiple births with rates highest for non-Hispanic whites; dramatic increases in births to women of advanced maternal age; and substantial increases in cesarean births."
Velez DR, Fortunato SJ, Thorsen P, Lombardi SJ, Williams SM, et al. (2008) Preterm Birth in Caucasians Is Associated with Coagulation and Inflammation Pathway Gene Variants. PLoS ONE 3(9): e3283.
"Spontaneous preterm birth (<37 weeks gestation—PTB) occurs in ~12% of pregnancies in the United States, and is the largest contributor to neonatal morbidity and mortality. ...These results support a role for genes in both the coagulation and inflammation pathways, and potentially different maternal and fetal genetic risks for PTB."
UK Nuffield Council on Bioethics report Critical care decisions in fetal and neonatal medicine: ethical issues
Australian NSW and ACT Consensus Statement
| Year | % less than 34 weeks | % 34-36 weeks | % total preterm |
1990 |
3.3 | 7.3 | 10.6 |
| 1995 | 3.3 | 7.7 | 11 |
| 2000 | 3.4 | 8.2 | 11.6 |
| 2005 | 3.6 | 9.1 | 12.7 |
Data from: Prevention of preterm birth: a renewed national priority Damus K. Curr Opin Obstet Gynecol. 2008 Dec;20(6):590-6
There have recently been in several countries independent studies on designing appropriate recommendations as to the clinical treatment of premature birth at specific ages of clinical gestation (differs by approximately 2 weeks from fertilization development). In most cases these recommendations are for very early births and in general based upon clinical outcomes (survival) at those ages.
International - World Health Organization; International Federation of Gynecology and Obstetrics (1993) 22–28 weeks or 500–1000 g birthweight as “threshold viability”
Australia - Perinatal care at the borderlines of viability: a consensus statement based on a NSW and ACT consensus workshop (2006) (More? Consensus Statement 2006)
Canada - Fetus and Newborn Committee, Canadian Paediatric Society; Maternal–Fetal Medicine Committee, Society of Obstetricians and Gynaecologists of Canada (1994) 23–25 weeks
United Kingdom - British Association of Perinatal Medicine (2000) < 26 weeks as “threshold viability” (More? Nuffield Council on Bioethics 2006)
USA - American Academy of Pediatrics; American College of Obstetricians and Gynecologists (2002) 23–25 weeks
(data from NSW and ACT Consensus Statement)
A series of recent studies have been looking at the relationship between spontaneous preterm birth (SPB) and genetic and other maternal and fetal factors.
Genetic regulation of amniotic fluid TNF-alpha and soluble TNF receptor concentrations affected by race and preterm birth. Menon R, Velez DR, Morgan N, Lombardi SJ, Fortunato SJ, Williams SM. Hum Genet. 2008 Sep 21.
Interleukin-6 (IL-6) and receptor (IL6-R) gene haplotypes associate with amniotic fluid protein concentrations in preterm birth.Velez DR, Fortunato SJ, Williams SM, Menon R. Hum Mol Genet. 2008 Jun 1;17(11):1619-30.
Perinatal care at the borderlines of viability: a consensus statement based on a NSW and ACT consensus workshop (February 2005) published in The Medical Journal of Australia 2006; 185 (9): 495-500.
< 23 weeks survival is minimal and the risk of major morbidity is so high that initiation of resuscitation is not appropriate.
23 weeks active treatment may be discussed, but would be discouraged in NSW/ACT neonatal intensive care units.
23 to 25 weeks otherwise normal infant, there is an increasing obligation to treat. However, it is acceptable medical practice not to initiate intensive care if parents so wish, following appropriate counselling.
24 weeks antenatal transfer to a tertiary centre for fetal reasons is indicated. The option of non-initiation of intensive care/resuscitation should be offered.
25 weeks active treatment is usually offered, but the option of non-initiation of intensive care/resuscitation (presence of adverse fetal factors such as twin-to-twin transfusion, intrauterine growth restriction or chorioamnionitis) should also be discussed.
26 weeks + otherwise normal infant the obligation to treat is very high, and treatment should generally be initiated unless there are exceptional circumstances.
(modified extract from Workshop Consensus Statement)
Links: eMJA Consensus Statement |
Nuffield Council on Bioethics report Critical care decisions in fetal and neonatal medicine: ethical issues
22 weeks extremely rare for babies born before this time survive. The Council recommends that intensive care should not be given to these babies at the current time, except as part of a pre-approved research study.
22 to 23 weeks about 1% of babies born survive to leave hospital. The Council recommends that normal practice should be not to give intensive care at this age, unless parents request it after a thorough discussion of the risks and if the doctors agree.
23 to 24 weeks difficult to predict whether babies will live, die, be healthy or have disabilities later on in life. Because of this uncertainty, the Council recommends that parents, after a thorough discussion with the healthcare team, should have the final say in whether intensive care is given.
24 to 25 weeks normal practice should be to give intensive care, unless the parents and the doctors agree that there is no hope of survival or if the level of suffering outweighs the baby’s interest in continuing to live.
25 weeks+ babies have a sufficiently high chance of surviving and low risk of developing severe disability. Intensive care should normally be given.
Active ending of life The Council has concluded that the active ending of life of newborn babies should not be allowed, no matter how serious their condition.
(modified extract from press release 15 Nov 06)
Links: Nuffield Council on Bioethics | BMJ News review article
A study has shown that risks of preterm birth in low abnormal birth weight (intrauterine growth restriction) and high (large for gestational age) categories are 2- to 3-fold greater than the risk among appropriate-for-gestational-age infants.
In another study of placenta previa, low birth weight is due mainly to preterm delivery and to a lesser extent with fetal growth restriction.
(More? HSTAT - Management of Preterm Labor)
Reference: Lackman F, Capewell V, Richardson B, daSilva O, Gagnon R. The risks of spontaneous preterm delivery and perinatal mortality in relation to size at birth according to fetal versus neonatal growth standards. Am J Obstet Gynecol. 2001 Apr;184(5):946-53.
Ananth CV, Demissie K, Smulian JC, Vintzileos AM. Relationship among placenta previa, fetal growth restriction, and preterm delivery: a population-based study. Obstet Gynecol. 2001 Aug;98(2):299-306.
A study has shown that risks of preterm birth in low abnormal birth weight (intrauterine growth restriction) and high (large for gestational age) categories are 2- to 3-fold greater than the risk among appropriate-for-gestational-age infants.
In another study of placenta previa, low birth weight is due mainly to preterm delivery and to a lesser extent with fetal growth restriction.
American Academy of Family Physicians The Newborn Examination: Part I. Emergencies and Common Abnormalities Involving the Skin, Head, Neck, Chest, and Respiratory and Cardiovascular Systems | Part II. Emergencies and Common Abnormalities Involving the Abdomen, Pelvis, Extremities, Genitalia, and Spine | Common Issues in the Care of Sick Neonates
American Medical Association "Kids Health" | Baby Development by Age
Links: Reviews | Articles | Online Textbooks | Search Textbooks | Search PubMed | Glossary
Reviews
Hack M, Fanaroff AA. Outcomes of children of extremely low birthweight and gestational age in the 1990's. Early Hum Dev. 1999 Jan;53(3):193-218.
Escobar GJ, Clark RH, Greene JD. Short-term outcomes of infants born at 35 and 36 weeks gestation: we need to ask more questions. Semin Perinatol. 2006 Feb;30(1):28-33.
Lorenz JM. The outcome of extreme prematurity. Semin Perinatol. 2001 Oct;25(5):348-59.
Articles
Chandiramani M, Shennan A. Preterm labour: update on prediction and prevention strategies. Curr Opin Obstet Gynecol. 2006 Dec;18(6):618-624.
Louis JM, Ehrenberg HM, Collin MF, Mercer BM. Perinatal intervention and neonatal outcomes near the limit of viability. Am J Obstet Gynecol. 2004 Oct;191(4):1398-402.
Search PubMed: Nov 2006 "preterm birth" 3,338 reference articles of which 625 were reviews.
Search PubMed Now: preterm birth | premature birth | premature labour
| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
Page 1 | birth page 2 | birth page 3 | birth page 4 | birth page 5 | birth page WWW
Home Page
Embryo stages
Fetal Dev
Dev Notes 1
Dev Notes 2
System Notes
Acknowledgements
Introduction
Birth Overview
Abnormalities
Caesarean
Apgar
Premature
Low Birth Weight
Placental Cord Clamping
Cardiovascular
Stillbirth and Perinatal Death
Molecular
Web Links
Movies
Class Notes
Serial Images
K12 Students
Abnormal
Embryology in the News
Histology
Site Map
School of Med Sci
UNSW Medicine
University of NSW
UNSW Cell Biology
NCBI Books
Dev Biol (Gilbert)
Page under development (notice removed when complete)
This page introduces concepts related to premature birth and the neonate and should give you a feel for the topic.
These notes should be considered in relation to Fetal Development timings.
Please email Dr Mark Hill if you wish to make a comment about this current project.