Medscape is available in 5 Language Editions – Choose your Edition here.



  • Author: Susan A Furdon, RNC, NNP-BC, MS; Chief Editor: Ted Rosenkrantz, MD  more...
Updated: Jan 02, 2016

Practice Essentials

Prematurity is a term for the broad category of neonates born at less than 37 weeks' gestation. Preterm birth is the leading cause of neonatal mortality and the most common reason for antenatal hospitalization.[1]  For premature infants born with a weight of less than 1000 g, the 3 primary causes of mortality are respiratory failure, infection, and congenital malformation. See the image below.

Preterm infant at 28 weeks' gestation. Note the sm Preterm infant at 28 weeks' gestation. Note the small amount of ear cartilage and/or flattened pinna.

Essential update: Study indicates that dexamethasone may affect hearing and intelligence in preterm infants

A meta-analysis by Ruolin et al indicated that dexamethasone use in preterm infants may have significant deleterious effects on hearing and intelligence. The study looked at ten randomized, controlled trials involving a total of 1038 preterm infants, including 512 who received intravenous dexamethasone and 526 who received a placebo. The investigators found a significantly lower intelligence quotient in patients who received dexamethasone treatment within seven days following birth, compared with the placebo group.[2]

In infants who began treatment with dexamethasone more than seven days after birth, the incidence of hearing loss was significantly greater than in the controls, although the change in intelligence quotient was comparable to that in the placebo group. The investigators also found that the incidence of cerebral palsy and visual impairment were similar in the dexamethasone and placebo groups whether dexamethasone was received within seven days following birth or later.[2]

Signs and symptoms

Confirmation of gestational age is based on physical and neurologic characteristics. The Ballard Scoring System remains the main tool clinicians use after delivery to confirm gestational age by means of physical examination.[3] The major parts of the anatomy used in determining gestational age include the following:

  • Ear cartilage (eg, a preterm infant at 28 weeks’ gestation has a small amount of ear cartilage and/or a flattened pinna)
  • Sole (eg, a preterm infant at 33 weeks’ gestation has only an anterior crease on the sole of the foot)
  • Breast tissue (eg, a preterm infant at 28 weeks’ gestation has no breast tissue, and the areolae are barely visible)
  • Genitalia

See Clinical Presentation for more detail.


Laboratory studies

Initial laboratory studies in cases of prematurity are performed to identify issues that, if corrected, improve the patient's outcome. Such tests include the following:

  • Complete blood count (CBC): May reveal anemia or polycythemia that is not clinically apparent
  • White blood cell (WBC) count: A high or low WBC count and numerous immature neutrophil types may be found; an abnormal WBC count may suggest subtle infection
  • Blood type and antibody testing (Coombs test): These studies are performed to detect blood-group incompatibilities between the mother and infant and to identify antibodies against fetal red blood cells (RBCs); such incompatibilities increase the risk for jaundice and kernicterus
  • Serum electrolyte levels: Frequent determination of serum sodium, potassium, and glucose concentrations, in conjunction with monitoring of daily weight and urine output in extremely low birth weight (ELBW) infants, assist the practitioner in determining fluid requirements

Imaging studies

Imaging studies are specific to the organ system affected. Chest radiography is performed to assess lung parenchyma in newborns with respiratory distress. Cranial ultrasonography is performed to detect occult intracranial hemorrhage in ELBW newborns. Prematurity itself is not an indication for an imaging study.

Lumbar puncture

Lumbar puncture is performed in infants with positive blood cultures and in those who have clinical signs of infection (presumed sepsis) and for whom a full course of antibiotic coverage is planned.

See Workup for more detail.


Stabilization in the delivery room with prompt respiratory and thermal management is crucial to the immediate and long-term outcome of premature infants, particularly extremely premature infants.

Respiratory management

  • Recruitment and maintenance of adequate or optimal lung volume; in infants with respiratory distress, this step may be accomplished with early continuous positive airway pressure (CPAP) given nasally, by mask (Neopuff), or by using an endotracheal tube when ventilation and/or surfactant is administered
  • Avoidance of hyperoxia and hypoxia by immediately attaching a pulse oximeter and, using an oxygen blender, keeping the oxygen saturation (SaO2) between 86% and 93%
  • Prevention of barotrauma or volutrauma by using a ventilator that permits measurement of the expired tidal volume and by keeping it at 4-7 mL/kg
  • Administration of surfactant early (< 2 hr of age) when indicated and prophylactically in all extremely premature neonates (< 29 wk)


In the intensive care nursery, radiant warmers may be used to compensate for heat loss in the premature infant. Incubators are more efficient than radiant warmers because the heated environment decreases heat loss due to conduction, convection, and radiation. In all nurseries, the environmental temperature should be maintained at more than 70°F (>21°C).

Fluid and electrolyte management

Preterm infants need intense monitoring of their fluid and electrolytes because of increased transdermal water loss and immature renal function in these infants, as well as various environmental issues (eg, radiant warming, phototherapy, mechanical ventilation). The degree of prematurity and the infant's specific medication problems dictate initial fluid therapy. However, the following general principles apply to all preterm infants:

  • Initial fluid should be a solution of glucose and water
  • Electrolytes should not be added until the infant is 24 hours of age, when urine output is adequate
  • Infants who develop acute tubular necrosis (ATN) should be treated with fluid restriction that equals insensible water loss plus urine output
  • Hyponatremia and weight gain should be treated with decreasing fluid administration

The patient's weight should be followed up every 24 hours. Results of laboratory monitoring and change in weight dictate changes in fluid and electrolyte support.

See Treatment and Medication for more detail.



Prematurity refers to the broad category of neonates born at less than 37 weeks' gestation. Preterm birth is the leading cause of neonatal mortality and the most common reason for antenatal hospitalization.[1] Although the estimated date of confinement (EDC) is 40 weeks' gestation, the World Health Organization (WHO) broadened the range of full term to include 37-42 weeks' gestation.

Premature newborns have many physiologic challenges when adapting to the extrauterine environment. Most articles in the neonatology section discuss in detail the most serious of these problems. Serious morbidities occur in extremely low birth weight (ELBW) infants. For more information, see Extremely Low Birth Weight Infant, Acute Respiratory Distress Syndrome, Bronchopulmonary Dysplasia, Periventricular Hemorrhage-Intraventricular Hemorrhage. The near-term neonate (34-36 weeks' gestation) has issues of prematurity that include feeding immaturity, temperature instability, and prolonged jaundice. This article provides a general overview of the premature infant.



Before birth, the placenta serves 3 major roles for the fetus: provision of all the nutrients for growth, elimination of fetal waste products, and synthesis of hormones that promote fetal growth.

With the exception of most electrolytes, the maternal circulation contains more substrate (eg, blood glucose) than the fetal circulation. In addition, the placenta is metabolically active and consumes glucose. Waste products of fetal metabolism (eg, heat, urea, bilirubin, carbon dioxide) are transferred across the placenta and eliminated by the mother's excretory organs (ie, liver, lung, kidneys, skin).

In addition, the placenta acts as a barrier to infection through mucosal macrophages and by allowing transfer of maternal immunoglobulins (immunoglobulins such as immunoglobulin G [IgG]) to the fetus beginning at 32-34 weeks' gestation. Placental dysfunction is involved in the transfer of IgG. Antibacterial activity of the amniotic fluid improves as gestational age advances.

Each of the immature organs of a premature infant has functional limitations. The tasks of caregivers in neonatal intensive care units (NICUs) are to recognize and monitor the needs of each infant and to provide appropriate support until functional maturity can be achieved.



United States

In the general population, an estimated 12% of infants are born prematurely, and about 50% of preterm births are preceded by preterm labor.[1]


No reliable numbers are available because different countries use different definitions of birth (eg, survival after birth, survival after 1 month).



Preterm births account for approximately 70% of neonatal deaths and 36% of infant deaths, as well as 25-50% of cases of long-term neurologic impairment in children.[1]

The mortality rate is high in developing countries, especially those of Sub-Saharan Africa. The perinatal mortality rate is 70 deaths per 1000 births; the neonatal mortality rate is 45 deaths per 1000 live births. Preterm birth is the strongest independent predictor of mortality in the United States. Preterm delivery accounts for 75-80% of all neonatal morbidity and mortality.

Since the early 1960s, survival rates of premature infants substantially increased because of technologic advances. From 1989-1990, infants with birth weights less than 751 g had a survival rate of 39% (range among centers, 23-48%). In 1992, the US Food and Drug Administration (FDA) approved exogenous surfactant therapy for respiratory distress syndrome (RDS), leading to a considerable improvement in survival rates. Since the FDA approved the use of surfactant and since the subsequent introduction of numerous natural surfactants, the mortality rate attributed to surfactant deficiency has been markedly reduced. See Acute Respiratory Distress Syndrome.

Data from the Vermont Oxford Network in 1994-1996 indicated that the survival rate of infants born weighing less than 1000 g was 74.9%.[4] Survival of infants born weighing less than 1000 g and requiring cardiopulmonary resuscitation in the delivery room was substantially decreased (53.8%). The changes in obstetric and neonatal care in the first half of the decade of 1990s decreased mortality and morbidity for ELBW infants. No additional improvements in mortality and morbidity were observed at the end of the decade.

Obstetric and pediatric personnel must be familiar with their own institutional data in addition to national benchmarks related to gestational age and mortality rates. These data are essential for proper prenatal counseling of parents and/or caregivers regarding survival and resuscitation plans.

The 3 primary causes of mortality in infants born with a weight of less than 1000 g are respiratory failure, infection, and congenital malformation. Infection of the amniotic fluid leading to pneumonia is the major cause of mortality.[3] In infants who weigh less than 500 g at birth, immaturity is listed as the only cause of mortality. See Ethical Issues in Neonatal Care.

Women who have an intrauterine infection do not respond to tocolytics. Preterm premature rupture of membranes (PPROM) is associated with 30-40% of premature deliveries. See Premature Rupture of Membranes. Mortality of the premature infant increases with coexisting PPROM but depends on gestational age and the expertise of the maternal-fetal monitoring team. Postnatal findings of periventricular leukomalacia (PVL) on cranial ultrasonography are highly correlated with chorioamnionitis.

In premature infants with a congenital heart defect (CHD), excluding isolated patent ductus arteriosus, the actuarial survival rate is 51% at 10 years, whereas infants with both CHD and prematurity have substantially worsened outcomes than infants who only have one of these conditions.[5] The survival rate improved as the study period (1976-1999) progressed. Congenital anomalies are an independent risk factor for mortality and morbidity in preterm birth.

In a longitudinal study of 1279 extremely premature children, (gestational age ≤28 wk; birth weight < 1250 g), Robertson et al found permanent hearing loss in 3.1% and severe-to-profound loss in 1.9%.[6] Among affected children, hearing loss was delayed in onset in 10% and progressive in 28%. Prolonged supplemental oxygen use was the most important marker for predicting hearing loss.

Werner et al. found, in a retrospective analysis of data from 20,231 live births recorded between 1995 and 2003, that very premature infants who are delivered vaginally have fewer breathing problems than do those delivered by cesarean section. All of the study’s infants were born after 24-34 weeks’ gestation, with 69.3% of them delivered vaginally. In comparison with the vaginally delivered infants, those delivered by cesarean section were more likely to be born in respiratory distress (39.2% compared with 25.6% for vaginal delivery). Infants in the study who underwent cesarean delivery were also more likely than vaginally delivered infants to have a 5-minute Apgar score of less than 7 (10.7% vs 5.8%, respectively).[7, 8]


Premature infants are born to women of every race. ELBW infants are most commonly born to women of low socioeconomic status, black women, teenaged female adolescents, and mothers older than 40 years. Women at highest risk of premature delivery can be assessed by using a scoring system that reviews their socioeconomic status, history, daily habits, and current pregnancy events.[5] About 30% of women with a high-risk score deliver prematurely compared with 2.5% of women with a low-risk score.

Primarily because of the increased incidence of preterm infants, the overall neonatal mortality rate in blacks in the United States is 2.3 times that of whites. Improvements in socioeconomic status and perinatal care have not improved the rate of prematurity and infant mortality rate in this population.


The results from one study (N=2549 neonates) noted that male infants born prematurely realized a higher risk of grade III/IV intraventricular hemorrhage, sepsis, and major surgery than premature females. A greater risk of mortality and poorer long-term neurologic outcome were also noted; however, sex-related differences for these appeared to lose significance at 27 weeks’ gestation.[9]

Female sex is associated with increased rates of survival of newborns born at 22-25 weeks' gestation.

Contributor Information and Disclosures

Susan A Furdon, RNC, NNP-BC, MS Neonatal Clinical Nurse Specialist/Nurse Practitioner, Department of Pediatrics, Albany Medical Center

Susan A Furdon, RNC, NNP-BC, MS is a member of the following medical societies: National Association of Neonatal Nurses, Sigma Theta Tau International

Disclosure: Nothing to disclose.


David A Clark, MD Chairman, Professor, Department of Pediatrics, Albany Medical College

David A Clark, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American Pediatric Society, Christian Medical and Dental Associations, Medical Society of the State of New York, New York Academy of Sciences, Society for Pediatric Research

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Arun K Pramanik, MD, MBBS Professor of Pediatrics, Louisiana State University Health Sciences Center

Arun K Pramanik, MD, MBBS is a member of the following medical societies: American Academy of Pediatrics, American Thoracic Society, National Perinatal Association, Southern Society for Pediatric Research

Disclosure: Nothing to disclose.

Chief Editor

Ted Rosenkrantz, MD Professor, Departments of Pediatrics and Obstetrics/Gynecology, Division of Neonatal-Perinatal Medicine, University of Connecticut School of Medicine

Ted Rosenkrantz, MD is a member of the following medical societies: American Academy of Pediatrics, American Pediatric Society, Eastern Society for Pediatric Research, American Medical Association, Connecticut State Medical Society, Society for Pediatric Research

Disclosure: Nothing to disclose.

Additional Contributors

Ted Rosenkrantz, MD Professor, Departments of Pediatrics and Obstetrics/Gynecology, Division of Neonatal-Perinatal Medicine, University of Connecticut School of Medicine

Ted Rosenkrantz, MD is a member of the following medical societies: American Academy of Pediatrics, American Pediatric Society, Eastern Society for Pediatric Research, American Medical Association, Connecticut State Medical Society, Society for Pediatric Research

Disclosure: Nothing to disclose.

  1. American College of Obstetricians and Gynecologists. Practice bulletin no. 159: management of preterm labor. Obstet Gynecol. 2016 Jan. 127 (1):e29-38. [Medline].

  2. Ruolin Z, Tao B, Li S, et al. Effect of dexamethasone on intelligence and hearing in preterm infants: a meta-analysis. Neural Regen Res. 2014. 9(6):637-45. [Full Text].

  3. Ballard JL, Khoury JC, Wedig K, et al. New Ballard Score, expanded to include extremely premature infants. J Pediatr. 1991 Sep. 119(3):417-23. [Medline].

  4. Barton L, Hodgman JE, Pavlova Z. Causes of death in the extremely low birth weight infant. Pediatrics. 1999 Feb. 103(2):446-51. [Medline].

  5. Creasy RK, Gummer BA, Liggins GC. System for predicting spontaneous preterm birth. Obstet Gynecol. 1980 Jun. 55(6):692-5. [Medline].

  6. Robertson CM, Howarth TM, Bork DL, Dinu IA. Permanent bilateral sensory and neural hearing loss of children after neonatal intensive care because of extreme prematurity: a thirty-year study. Pediatrics. 2009 May. 123(5):e797-807. [Medline].

  7. Pittman G. Vaginal delivery safer for many preemies: study. Medscape News. Available at May 8 2013; Accessed: 5 Jun 2013.

  8. Werner EF, Han CS, Savitz DA, et al. Health outcomes for vaginal compared with cesarean delivery of appropriately grown preterm neonates. Obstet Gynecol. June 2013. 121(6):1195-200.

  9. Kent AL, Wright IM, Abdel-Latif ME. Mortality and Adverse Neurologic Outcomes Are Greater in Preterm Male Infants. Pediatrics. 2012 Jan. 129(1):124-131. [Medline].

  10. Dubowitz LM, Dubowitz V, Goldberg C. Clinical assessment of gestational age in the newborn infant. J Pediatr. 1970 Jul. 77(1):1-10. [Medline].

  11. Hittner HM, Hirsch NJ, Rudolph AJ. Assessment of gestational age by examination of the anterior vascular capsule of the lens. J Pediatr. 1977 Sep. 91(3):455-8. [Medline].

  12. Fritz MA. Infertility treatment and the multifetal gestation epidemic: too much of a good thing. Contemporary OB-GYN. 2002. 65-90.

  13. Conde-Agudelo A, Romero R. Cervical phosphorylated insulin-like growth factor binding protein-1 test for the prediction of preterm birth: a systematic review and metaanalysis. Am J Obstet Gynecol. 2016 Jan. 214 (1):57-73. [Medline].

  14. Conde-Agudelo A, Romero R. Predictive accuracy of changes in transvaginal sonographic cervical length over time for preterm birth: a systematic review and metaanalysis. Am J Obstet Gynecol. 2015 Dec. 213 (6):789-801. [Medline].

  15. [Guideline] Stark AR. Levels of neonatal care. Pediatrics. 2004 Nov. 114(5):1341-7. [Medline].

  16. Fuchs H, Lindner W, Leiprecht A, Mendler MR, Hummler HD. Predictors of early nasal CPAP failure and effects of various intubation criteria on the rate of mechanical ventilation in preterm infants of 1111Arch Dis Child Fetal Neonatal Ed</i>. 2011 Sep. 96(5):F343-7. [Medline].

  17. Emery G. High-Flow Nasal Cannulae Not Inferior to CPAP for Extubated Preterm Infants. Medscape. Oct 9 2013. [Full Text].

  18. Manley BJ, Owen LS, Doyle LW, et al. High-flow nasal cannulae in very preterm infants after extubation. N Engl J Med. Oct 10 2013. 369(15):1425-33. [Medline].

  19. American Academy of Pediatrics Committee on Fetus and Newborn. Respiratory support in preterm infants at birth. Pediatrics. 2014 Jan. 133(1):171-4. [Medline]. [Full Text].

  20. Fox S. AAP backs CPAP plus selective surfactants in premies. Medscape Medical News. December 30, 2013. [Full Text].

  21. Fox S. Delivery Room Guidelines Improve Outcomes for Preemies. Medscape Medical News. Available at Accessed: September 23, 2013.

  22. Demauro SB, Douglas E, Karp K, Schmidt B, Patel J, Kronberger A, et al. Improving Delivery Room Management for Very Preterm Infants. Pediatrics. 2013 Sep 16. [Medline].

  23. Boggs W. Newborn health advocates propose acceleration of kangaroo mother care. Reuters Health Information. December 4, 2013. [Full Text].

  24. Engmann C, Wall S, Darmstadt G, Valsangkar B, Claeson M. Consensus on kangaroo mother care acceleration. Lancet. 2013 Nov 30. 382(9907):e26-7. [Medline].

  25. Novak B. Chromium Supplements Boost Glucose Tolerance and Calorie Absorption in Preemies. Medscape Medical News. Available at Accessed: February 4, 2014.

  26. Kapoor V, Glover R, Malviya MN. Alternative lipid emulsions versus pure soy oil based lipid emulsions for parenterally fed preterm infants. Cochrane Database Syst Rev. 2015 Dec 2. 12:CD009172. [Medline].

  27. Abrams SA; Committee on Nutrition. Calcium and vitamin D requirements of enterally fed preterm infants. Pediatrics. May 2013;131(5):e1676-83. [Medline].

  28. Hand L. Guidelines: Preterm Infants Require Vitamin D Supplement. Medscape Medical News. Apr 29 2013. Available at Accessed: May 9 2013.

  29. Hand L. Darbepoetin Reduces Transfusion Needs in Preterm Infants. Medscape News. Available at Accessed: June 24, 2013.

  30. Ohls RK, Christensen RD, Kamath-Rayne BD, Rosenberg A, Wiedmeier SE, Roohi M, et al. A Randomized, Masked, Placebo-Controlled Study of Darbepoetin Alfa in Preterm Infants. Pediatrics. 2013 Jun 17. [Medline].

  31. Roberts G, Anderson PJ, De Luca C, Doyle LW. Changes in neurodevelopmental outcome at age eight in geographic cohorts of children born at 22-27 weeks' gestational age during the 1990s. Arch Dis Child Fetal Neonatal Ed. 2010 Mar. 95(2):F90-4. [Medline].

  32. 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 Dec 7. 306(21):2348-58. [Medline].

  33. Allen MC, Alexander GR, Tompkins ME, Hulsey TC. Racial differences in temporal changes in newborn viability and survival by gestational age. Paediatr Perinat Epidemiol. 2000 Apr. 14(2):152-8. [Medline].

  34. Alme AM, Mulhern ML, Hejkal TW, et al. Outcome of rtinopath of prematurity patients following adoption of revised indications for treatment. BMC Ophthalmol. Nov 2008. 13:8:23. [Medline].

  35. Anand KJ, Hall RW, Desai N, et al. Effects of morphine analgesia in ventilated preterm neonates: primary outcomes from the NEOPAIN randomised trial. Lancet. May 2004. 363:1673-1682. [Medline].

  36. Andres RL, Day MC. Perinatal complications associated with maternal tobacco use. Semin Neonatol. 2000 Aug. 5(3):231-41. [Medline].

  37. Barrington KJ, Finer NN. Inhaled Nitric Oxide for Respiratory Failure in Preterm Infants. Cochrane Database System. January 2006. 25:CD000509. [Medline].

  38. Beckerman KP. Protease inhibitor treatment of HIV-1-infected women may protect against extreme prematurity and very low birth weight. J Infect Dis. Oct 2007. 196:1270-1271. [Medline].

  39. Bell EF. Preventing Necrotizing Enterocolitis: What Works and How Safe. Pediatrics. January 2005. 115:173-174. [Medline].

  40. Bell EF. When to transfuse preterm babies. Arch Dis Child Fetal Neonatal Ed. Nov 2008. 93:F469-473. [Medline].

  41. Bernstein IM, Horbar JD, Badger GJ, et al. Morbidity and mortality among very-low-birth-weight neonates with intrauterine growth restriction. The Vermont Oxford Network. Am J Obstet Gynecol. 2000 Jan. 182(1 Pt 1):198-206. [Medline].

  42. Bhandari V, Bergqvist LL, Kronsberg SS, et al. Morphine Administration and Short-Term Pulmonary Outcomes Among Ventilated Preterm Infants. Pediatrics. August 2005. 116:352-359. [Medline].

  43. Boggs W. Automatic Oxygen Control System Improves Oxygen Delivery in Preterm Infants. Medscape [serial online]. Available at Accessed: February 21, 2014.

  44. Borna S, Saeidi FM. Celecoxib versus magnesium sulfate to arrest preterm labor: randomized trial. J Obstet Gynaecol Res. Oct 2007. 33:631-634. [Medline].

  45. Boulet SL, Schieve LA, Nannini A, et al. Perinatal outcomes of twin births conceived using assisted reproduction technology: a population-based study. Hum Reprod. Aug 2008. 23:1941-1948. [Medline].

  46. Chiswick M. Infants of borderline viability: ethical and clinical considerations. Semin Fetal Neonatal Med. Feb 2008. 13:8-15. [Medline].

  47. Clarke P, Mitchell SJ, Wynn R, et al. Vitamin K prophylaxis for preterm infants: a randomized, controlled trial of 3 regimens. Pediatrics. Dec 2006. 118:e1657-1666. [Medline].

  48. Cole CH. Prevention of Prematurity: Can We Do It in America?. Pediatrics. Aug 1985. 76:310-312. [Medline].

  49. Connolly G, Byrne P. Teenage pregnancies and risk of late fetal death and infant mortality. Br J Obstet Gynaecol. 1999 Nov. 106(11):1230. [Medline].

  50. Cotter AM, Garcia AG, Duthely ML, et al. Is antiretroviral therapy during pregnancy associated with an increased risk of preterm delivery, low birth weight, or stillborn?. J Infect Dis. May 2006. 193:1195-1201. [Medline].

  51. Crowther CA, Haslam RR, Hiller JE, et al. Neonatal Respiratory Distress Syndrome after Repeat Exposure to antenatal corticosteriods: a randomised controlled trial. Lancet. Jun 2006. 367:1913-1919. [Medline].

  52. Dees E, Lin H, Cotton RB, et al. Outcome of preterm infants with congenital heart disease. J Pediatr. 2000 Nov. 137(5):653-9. [Medline].

  53. Doron MW, Veness-Meehan KA, Margolis LH, et al. Delivery room resuscitation decisions for extremely premature infants. Pediatrics. 1998 Sep. 102(3 Pt 1):574-82. [Medline].

  54. Doyle LW, Davis PG, Morley CJ, et al. Outcome at 2 years of age of infants from the DART study: a multicenter, international, randomized, controlled trial of low-dose dexamethasone. Pediatrics. April 2007. 119:716-721. [Medline].

  55. Doyle LW, Halliday HL, Ehrenkranz RA, et al. Impact of Postnatal Systemic Corticosteroids on Mortality and Cerebral Palsy in Preterm Infants: Effect Modification by Risk for Chronic Lung Disease. Pediatrics. March 2005. 115:655-661. [Medline].

  56. Durnwald CP, Walker H, Lundy JC, et al. Rates of Recurrent Preterm Birth by Obstetrical History and Cervical Length. Am J Obstet Gynecol. September 2005. 193:1170-1174. [Medline].

  57. El-Metwally D, Vohr B, Tucker R. Survival and neonatal morbidity at the limits of viability in the mid 1990s: 22 to 25 weeks. J Pediatr. 2000 Nov. 137(5):616-22. [Medline].

  58. Escobar GJ, Clark RH, Greene JD. Short-Term Outcomes of Infants Born at 35 and 36 Weeks Gestation: We Need to Ask More Questions. Seminars in Perinatology. February 2006. 30:28-33. [Medline].

  59. Fanaroff AA, Stoll BJ, Wright LL, et al. Trends in Neonatal Morbidity and Mortality for Very Low Birthweight Infants. American Journal of Obstetrics and Gynecology. February 2007. 196:e1-8. [Medline].

  60. Finer NN, Horbar JD, Carpenter JH. Cardiopulmonary resuscitation in the very low birth weight infant: the Vermont Oxford Network experience. Pediatrics. 1999 Sep. 104(3 Pt 1):428-34. [Medline].

  61. Foix-L'Helias L, Marret S, Ancel PY, et al. Impact of the use of antenatal corticosteroids on mortality, cerebral lesions and 5-year neurodevelopmental outcomes of very preterm infants: the EPIPAGE cohort study. BJOG. January 2008. 115:275-282. [Medline].

  62. Furdon SA, Lapitsky J, Diven S, Horgan MJ. Effect of standardized approach to the care of the extremely low birthweight infant. J Nurs Care Qual. 1997 Aug. 11(6):42-51. [Medline].

  63. Gracey K, Talbot D, Lankford R, Dodge P. Family teaching toolbox. Nasal cannula home oxygen. Adv Neonatal Care. 2003 Apr. 3(2):99-101. [Medline].

  64. Groh-Wargo S, Hovasi Cox J. Nutritional Care for High-Risk Newborns. 3rd ed. Los Angeles, CA: Bonus; 2000.

  65. Gross SJ, Anbar RD, Mettelman BB. Follow-up at 15 Years of Preterm Infants from a Controlled Trial of Moderately Early Dexamethasone for the Prevention of Chronic Lung Disease. Pediatrics. March 2005. 115:681-687. [Medline].

  66. Hallenberger A, Poets CF, Horn W, Seyfang A, Urschitz MS. Closed-Loop Automatic Oxygen Control (CLAC) in Preterm Infants: A Randomized Controlled Trial. Pediatrics. 2014 Feb. 133(2):e379-85. [Medline].

  67. Halliday HL, Ehrenkranz RA, Doyle LW. Early (< 8 days) postnatal corticosteroids for preventing chronic lung disease in preterm infants. Cochrane Database Syst Re. Jan 2009. 21:CD001146. [Medline].

  68. Hellgren K, Hellstrom A, Jacobson L, et al. Visual and cerebral sequelae of very low birth weight in adolescents. Arch Dis Child Fetal Neonatal Ed. Jul 2007. 92:F259-264. [Medline].

  69. Hodnett ED. Support during pregnancy for women at increased risk. Cochrane Database Syst Rev. 2000. (2):CD000198. [Medline].

  70. Holditch-Davis D, Merrill P, Schwartz T, et al. Predictors of wheezing in prematurely born children. J Obstet Gynecol Neonatal Nurs. May-Jun 2008. 37:262-273. [Medline].

  71. Horbar JD, Badger GJ, Carpenter JH, et al. Trends in mortality and morbidity for very low birth weight infants, 1991-1999. Pediatrics. 2002 Jul. 110(1 Pt 1):143-51. [Medline].

  72. Huxley R, Owen GG, Whincup PH, et al. Is Birth Weight a Risk Factor for Ischemic Heart Disease in Later Life?. Am J Clin Nutr. May 2007. 85:1244-1250. [Medline].

  73. Johnston CC, Stevens B, Pinelli J, et al. Kangaroo Care is Effective in Diminishing Pain Response in Preterm Neonates. Arch Pediatr Adolesc Med. November 2003. 157:1084-1088. [Medline].

  74. Juul SE, McPherson RJ, Bauer LA, et al. A phase I/II trial of high-dose erythropoietin in extremely low birth weight infants: pharmocokinetics and safety. Pediatrics. Aug 2008. 122:383-391. [Medline].

  75. Klaus MH, Fanaroff AA. Care of the High-Risk Neonate. 5th ed. Philadelphia, PA: WB Saunders; 2001.

  76. Kogan MD, Alexander GR, Kotelchuck M, et al. Trends in twin birth outcomes and prenatal care utilization in the United States, 1981-1997. JAMA. 2000 Jul 19. 284(3):335-41. [Medline].

  77. Kraybill EN. Ethical issues in the care of extremely low birth weight infants. Semin Perinatol. 1998 Jun. 22(3):207-15. [Medline].

  78. Kulmala T, Vaahtera M, Ndekha M, et al. The importance of preterm births for peri- and neonatal mortality in rural Malawi. Paediatr Perinat Epidemiol. 2000 Jul. 14(3):219-26. [Medline].

  79. Larsson PG, Fahraeu L, Carlsson B, et al. Late miscarriage and preterm birth after treatment with clindamycin: a randomised consent design study according to Zelen. BJOG. Jun 2006. 113:629-37. [Medline].

  80. Lin HC, Su BH, Chen AC, et al. Oral Probiotics Reduce the Incidence and Severity of Necrotizing Enterocolitis in Very Low Birth Weight Infants. Pediatrics. January 2005. 115:1-4. [Medline].

  81. Lindstrom K, Winbladh B, Haglund B, et al. Preterm Infants as Young Adults: A Swedish National Cohort Study. Pediatrics. July 2007. 120:70-77. [Medline].

  82. Linhart Y, Bashiri A, Maymon E, et al. Congenital anomalies are an independent risk factor for neonatal morbidity and perinatal mortality in preterm birth. Eur J Obstet Gynecol Reprod Biol. 2000 May. 90(1):43-9. [Medline].

  83. Lund C, Kuller J, Lane A, et al. Neonatal skin care: the scientific basis for practice. Neonatal Netw. 1999 Jun. 18(4):15-27. [Medline].

  84. Maguire CM, Veen S, Sprij AJ, et al. Effects of basic developmental care on nenoatal morbidity, neuromotor development, and growth at term age of infants who were born at 11Pediatrics</i>. Feb 2008. 121:e239-245. [Medline].

  85. Mahomed K, Bhutta Z, Middleton P. Zinc supplementation for improving pregnancy and infant outcome. Cochrane Database Syst Rev. Apr 2007. 2:CD000230. [Medline].

  86. Malloy MH, Freeman DH. Respiratory distress syndrome mortality in the United States, 1987 to 1995. J Perinatol. 2000 Oct-Nov. 20(7):414-20. [Medline].

  87. March of Dimes. Peristats. Available at Accessed: Oct 1, 2006.

  88. Marret S, Marpeau L, Zupan-Simunek V, et al. Magnesium sulfate given before very-preterm birth to protect infant brain: the randomised controlled PREMAG trial*. BJOG. Mar 2007. 114:310-318. [Medline].

  89. Martin JA, Hamilton BE, Sutton PD, et al. Births: Final Data for 2006. National Vital Statistics Reports. Jan 2009. 57:1-104.

  90. Martin JA, Kung HC, Mathews TJ, Hoyert DL, Strobino DM, Guyer B, et al. Annual summary of vital statistics. 2006. Pediatrics. 2008. 121(4):788-801. [Medline].

  91. McCall EM, Alderdice FA, Halliday HL, et al. Interventions to prevent hypothermia at birth in preterm and/or low birthweight infants. Cochrane Database Syst Rev. Jan 2008. 1:CD004210. [Medline].

  92. Meirowitz NB, Ananth CV, Smulian JC, Vintzileos AM. Effect of labor on infant morbidity and mortality with preterm premature rupture of membranes: United States population-based study. Obstet Gynecol. 2001 Apr. 97(4):494-8. [Medline].

  93. Mercer B, Milluzzi C, Collin M. Periviable birth at 20 to 26 weeks of gestation: proximate causes, previous obstetric history and recurrence risk. Am J Obstet Gynecol. September 2005. 193:1175-1180. [Medline].

  94. Mestan KK, Marks JD, Hecox K, et al. Neurodevelopmental Outcomes of Premature Infants Treated with Inhaled Nitric Oxide. N Engl J Med. July 2005. 353:23-32. [Medline].

  95. Moore ML. Preterm Labor and Birth: What Have We Learned in the Past Two Decades. J Obstet Gynecol Neonatal Nurs. Sept.-Oct. 2003. 32:638-49. [Medline].

  96. Murakami Y, Jain A, Silva RA, et al. Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP): 12-month experience with telemeidicine screening. Br J Ophthalmol. Nov 2008. 92:1456-1460. [Medline].

  97. Ohlsson A, Aher SM. Early erythropoietin for preventing red blood cell transfusion in preterm and/or low birth weight infants. Cochrane Database Syst Rev. Jul 2006. 19:CD004863. [Medline].

  98. Osborn DA, Evans N. Early Volume Expansion for Prevention of Morbidity and Mortality in Very Preterm Infants. Cochrane Datatbase System. 2004. 2:CD002055. [Medline].

  99. Peltoniemi OM, Kari MA, Tammela O, et al. Randomized trial of a single repeat dose of prenatal betamethasone treatment in imminent preterm birth. Pediatrics. Feb 2007. 119:290-298. [Medline].

  100. Pool V, Iskander J. Saftey of Influenza Vaccination During Pregnancy. Am J Obstet Gynecol. April 2006. 194:1200. [Medline].

  101. Rautava L, Lehtonen L, Peltola M, et al. The effect of birth in secondary- or tertiary-level hospitals in Finland on mortality in very preterm infants: a birth-register study. Pediatrics. Jan 2007. 119:e257-263. [Medline].

  102. Raydo LL, Reu-Donlon CM. Putting Babies "Back to Sleep": Can we do better?. Neonatal Network. 2005. 24:9-16.

  103. Robertson CMT, Watt M-J, Yasui Y. Changes in the Prevalence of Cerebral Palsy for Children Born Very Prematurely Within a Population-Based Program Over 30 Years. JAMA. June 2007. 297:2733-2740. [Medline].

  104. Romero R. Prevention of spontaneous preterm birth: the role of sonographic cervical length in identifying patients who may benefit from progesterone treatment. Ultrasound Obstet Gynecol. October 2007. 30:675-686. [Medline].

  105. Rudge MV, Calderon IM, Ramos MD, et al. Perinatal outcome of pregnancies complicated by diabetes and by maternal daily hyperglycemia not related to diabetes. A retrospective 10-year analysis. Gynecol Obstet Invest. 2000. 50(2):108-12. [Medline].

  106. Schieve LA, Cohen B, Nannini A, et al. A population-based study of maternal and perinatal outcomes associated with assisted reproductive technology in Massachusetts. Matern Child Health J. Nov 2007. 11:517-525. [Medline].

  107. Schreiber MD, Gin-Mestan K, Marks JD, et al. Inhaled Nitric Oxide in Premature Infants with the Respiratory Distress Syndrome. N Engl J Med. November 2003. 349:2099-2107. [Medline].

  108. Schulte J, Domingues K, Sukalac T, et al. Declines in low birth weight and preterm birth among infants who were born to HIV-infected women during an era of increased use of maternal antiretroviral drugs: Pediatric Spectrurm of HIV Disease, 1989-2004. Pediatrics. Apr 2007. 119:e900-906. [Medline].

  109. Sibai BM, Caritis S, Hauth J, et al. Risks of preeclampsia and adverse neonatal outcomes among women with pregestational diabetes mellitus. National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Units. Am J Obstet Gynecol. 2000 Feb. 182(2):364-9. [Medline].

  110. Simoes EA, Groothuis JR, Carbonell-Estrany X, et al. Palivizumab prophylaxis, respiratory syncytial virus, and subsequent recurrent wheezing. J Pediatr. Jul 2007. 151:34-42, 42e1. [Medline].

  111. Smith GN, Walker MC, Ohlsson A, et al. Randomized double-blind placebo-controlled trial of transdermal nitroglycerin for preterm labor. Am J Obstet Gynecol. Jan 2007. 196:e1-8. [Medline].

  112. Stevens B, Yamada J, Ohlsson A. Sucrose for Analgesia in Newborn Infants Undergoing Painful Procedures. Cochrane Database System Rev. 2004. 3:CD001069. [Medline].

  113. Stupin JH, David M, Siedentopf JP, et al. Emergency cerclage versus bed rest for amniotic sac prolapse before 27 gestational weeks. A retrospective, comparative study of 161 women. Eur J Obstet Gynecol Reprod Biol. July 2008. 139:32-37. [Medline].

  114. Suzuki K, Tanaka T, Kondo N, et al. Is maternal smoking during early pregnance a risk factor for all low birth weight infants?. J Epidemiol. May 2008. 18:89-96. [Medline].

  115. Tyson JE, Kennedy KA. Trophic Feedings for Parenterally Fed Infants. Cochrane Database Syst Rev. July 2005. 3:CD000504. [Medline].

  116. van Wassenaer AG, Westera J, Houtzager BA, et al. Ten-year follow-up of children born at 111111111111111Pediatrics</i>. November 2005. 116:e613-618. [Medline].

  117. Ventolini G, Neiger R, Hood DL, et al. Changes in the threshold of fetal lung maturity testing and neonatal outcome of infants delivered electively before 39 weeks gestation: implications and cost-effectiveness. J Perinatol. May 2006. 26:264-267. [Medline].

  118. Ventolini G, Neiger R, Mathes L, et al. Incidence of respiratory disorders in neonates born between 34 and 36 weeks of gestation following exposure to antenatal corticosteroids between 24 and 34 weeks of gestation. Am J Perinatol. February 2008. 25:79-83. [Medline].

  119. Westrup B, Bohm B, Lagercrantz H, et al. Preschool Outcome in Children Born Very Prematurely and Cared for According to the Newborn Individualized Care and Assessment Program (NIDCAP). Acta Paediatr. April 2004. 93:498-507. [Medline].

  120. Wright VC, Schieve LA, Reynolds MA, et al. Assisted Reproductive Technology Surveillance-United States, 2001. MMWR Surveill Summ. April 2004. 53:1-20. [Medline].

  121. Ziadeh SM. The outcome of triplet versus twin pregnancies. Gynecol Obstet Invest. 2000. 50(2):96-9. [Medline].

  122. Stone WL, Shah D, Hollinger SM. Retinopathy of prematurity: an oxidative stress neonatal disease. Front Biosci (Landmark Ed). 2016 Jan 1. 21:165-77. [Medline].

  123. Ross GS, Foran LM, Barbot B, Sossin KM, Perlman JM. Using cluster analysis to provide new insights into development of very low birthweight (VLBW) premature infants. Early Hum Dev. 2016 Jan. 92:45-9. [Medline].

Preterm infant at 28 weeks' gestation. Note the small amount of ear cartilage and/or flattened pinna.
Preterm infant at 33 weeks' gestation. Note the increased cartilage, recoil, and outer ridge curving inward.
A term infant has well-developed cartilage with instant recoil.
Preterm infant at 28 weeks' gestation. Note the flat sole.
Preterm infant at 33 weeks' gestation. Note the presence of only an anterior crease.
Term gestation. Note the multiple creases.
Preterm infant at 28 weeks' gestation. No breast tissue is present, and the areolae are barely visible.
Preterm infant at 33 weeks' gestation. The breast tissue is less than 1 cm, and the areolae are raised and/or pigmented.
All material on this website is protected by copyright, Copyright © 1994-2016 by WebMD LLC. This website also contains material copyrighted by 3rd parties.