- CI: confidence interval
- CLD: chronic lung disease
- ELGA: extremely low gestational age
- IVH: intraventricular hemorrhage
- MDI: Mental Development Index
- NICHD: National Institute of Child Health and Human Development
- NICU: neonatal intensive care unit
- PVL: periventricular leukomalacia
- ROP: retinopathy of prematurity
- SD: standard deviation
Drs Ho and Saigal did not disclose any relationships relevant to this article.
After completing this article, readers should be able to:
Describe the current survival and neonatal morbidity among infants of borderline viability.
Delineate the neurodevelopmental morbidity in the first 2 to 3 years after birth.
Appreciate the methodologic problems and difficulties in conducting and reviewing longitudinal studies on outcomes.
Explain how different perinatal management approaches affect outcomes.
Describe the impact of major neonatal morbidities on neurodevelopmental outcome.
Due to the combined efforts of obstetricians and neonatologists in optimizing perinatal and neonatal care, survival of infants at the threshold of viability has improved remarkably in the last decade. Neonatal intensive care is being offered to more and more immature infants. In addition, obstetricians appear to be more willing to intervene earlier due to the ability to perform more accurate assessments of gestational age, (1) the widespread use of antenatal corticosteroids (2) and postnatal surfactant, (3) and more heroic interventions such as cesarean delivery for a compromised fetus. (4)(5) This combination has resulted in an increase in the absolute number of survivors of extremely low gestational age (ELGA). At the same time, due to the high rates of disabilities in the face of increasing costs of providing neonatal intensive care, the debate continues over whether intensive care is justified for ELGA infants. (6)(7)(8) Thus, because of the rapid progress in both obstetric and neonatal care and the changing outcomes, it is vital to continue to evaluate the recent survivors. Fortunately, several recent publications address the early outcomes of regional cohorts of tiny infants based on reliable gestational age data. In addition, data are available on large cohorts from network studies around the world. Hack and Fanaroff (9) reviewed the outcomes of infants younger than 26 weeks gestational age or less than 800 g birthweight born in the early 1990s. This article updates the outcomes of the same group of extremely immature infants born since the mid- to late 1990s and addresses both survival and short-term neonatal and neurodevelopmental morbidity.
Population-based studies on the outcome of extremely immature infants, although more difficult to conduct, are the most valid study design for the evaluation of neonatal intensive care. Such studies can minimize selection bias by encompassing all births within a geographic area and, thus, provide a more accurate account than single institution or network data. Survival from regional studies, (10) however, generally is lower than that seen with hospital-based or network studies (11) because they include infants who die before being transferred to a tertiary care center or for whom intensive care either was not initiated electively or was unsuccessful due to the lack of resources and expertise. In an innovative systematic review, Evans and Levene (12) have shown that the potential for overestimating survival by using data from selective reports of neonatal admissions versus all births or all livebirths can be as high as 100% and 56%, at 23 and 24 weeks, respectively. They recommend that future studies endeavor to report the outcome of all pregnancies for each week of gestation, including terminations, miscarriages, stillbirths, and livebirths, to minimize this substantial bias.
Single-institution studies may include inborn or outborn infants and are subject to changes in referral pattern. Some centers use within-institution data of inborn infants or neonatal intensive care unit (NICU) admissions for counseling parents about the prognosis of infants who are likely to deliver in their institution and for purposes of annual audit. The recent network studies from the United States (11)(13) and Canada (14)(15) have the advantage of providing outcomes on a very large number of extremely immature infants. These studies are important for benchmarking of quality of care between centers during a given period, examining neonatal outcomes related to variations in practice, and developing protocols and research concepts to improve the quality of care of newborns. (16) However, they do not provide data that can be generalized with regard to outcomes. It is also not possible to use these data to examine time trends. Thus, there are strengths and limitations to each of these cohort studies, and it is important to use the appropriate study design and population for the question posed.
In the past, survival and outcomes generally were reported by birthweight, which always can be measured accurately. Until recently, gestational age estimates were unreliable. It is recognized increasingly that data based on gestational age are more appropriate for making decisions about the timing and mode of delivery and aggressiveness of obstetric and neonatal interventions as well as counseling parents about projected survival and future disability of their infants. However, inaccuracies in dating that is unconfirmed by ultrasonography can result in significantly higher or lower survival rates, particularly at very low gestational ages. (17) Accuracy of gestational age has improved due to the routine use of early ultrasonography. (1) Gestational age currently is reported according to World Health Organization guidelines by completed weeks, rather than the earlier practice of rounding off to the nearest week of gestation. These apparently minor variations in reporting practices can have a significant impact on survival statistics. Indeed, at very early gestational ages, survival may improve with each additional day of gestation (eg, 22 1/7 versus 22 5/7 wk). (18)
An international consensus on the standardization of reporting morbidity with regard to the most appropriate age for a reliable assessment, minimum data set required, and methods and tools for assessment has yet to be reached. Some headway in this direction has been made in the United Kingdom by the National Perinatal Epidemiology Unit in terms of a structured format for reporting health status at 2 years. (19) Similarly, the National Institute of Child Health and Human Development (NICHD) Neonatal Research Network has strict standardized protocols of neurologic and developmental assessments and interview format at 18 months corrected age. (16) High attrition rates, which plagued many previous studies, have been addressed, and most investigators now strive for a compliance of greater than 80%. (11) Several investigators have reported that disability rates are disproportionately high among those who are lost to follow-up, (20)(21) although it appears that the converse also can be true. Using a predictive model and a large United States cohort of survivors whose birthweights ranged from 401 to 1,000 g, those who were compliant with follow-up assessments had significantly lower Bayley II Mental Development Index (MDI) scores compared with those who were lost to follow-up. (22) In the past, there was considerable criticism of the lack of methodologically sound studies. (23) Although some concerns remain, recent investigators have expended considerable effort to minimize biases in reporting current data.
Search Protocol and Problems Encountered
A MEDLINE search was conducted of the English literature using the following MESH headings: “follow-up,” “outcomes,” “premature,” “preterm,” and “low birthweight.” All studies of births at less than 26 weeks gestational age occurring during the mid-1990s and later were identified. Studies reported by birthweight were included only for the subgrouping of infants weighing less than 750 g (800 g in one study) so as to be comparable to less than 26 weeks gestational age. Studies that had small sample sizes (<100) for the target gestational age of 22 to 25 weeks were excluded (24)(25)(26) (except for those reporting on a single subgroup [eg, ≤23 weeks’ gestation or ≤500 g infants]). Some studies were excluded if the number of births and survivors could not be extracted for each gestational week or by 100-g subgroups or if the data were reported as cumulative survival. (27)(28)(29) Studies in which the same data were presented in different papers were excluded to avoid duplication bias.
The reporting of outcomes was not uniform, making comparisons and collation difficult. The cohorts were heterogeneous, with the denominators used for calculating survival varying from all births (livebirths and stillbirths) to livebirths alone or NICU admissions (inborn or outborn births). Although it is important to account for all births, including delivery room deaths, sometimes they were not included in the denominator of the overall survival figures, even when they were reported. (14)(30) In some studies, delivery room deaths comprised as many as 42% of all births at 25 weeks and younger gestational age. (14) As illustrated by Kamper and associates, (31) inclusion of only infants who were resuscitated at birth or admitted to the NICU results in higher survival rates than would be otherwise.
Where both stillbirths and livebirths were included, sometimes no data were presented to separate the number of infants within the two groups. (32)(33) Although histograms/figures are visually appealing, it is difficult to obtain the actual figures unless the number of survivors/denominator for each gestational age/birthweight group also are provided (we took the liberty of extrapolating some numbers from histograms, which may affect the accuracy). (34)(35) Most investigators reported on survival of infants to primary hospital discharge, but a few reported on survival to a specified time period (eg, 1 or 2 y). (35)(36) Reports on outcomes by birthweight varied slightly with different birthweight ranges: 500 to 749 g, (35)(37) 501 to 750 g, (13) and less than 500 g (15)(38) or 401 to 500 g. (34)(39) These variations and discrepancies in reporting outcomes are challenging for individuals who perform systematic reviews or meta-analyses. (40)
Survival by Gestational Age
Even within population-based studies, there is considerable variation in survival rates among different geographic areas, probably due to differences in practices of initiating intensive care. Survival of infants between 22 and 25 weeks’ gestational age ranged from 26% to 69% (Table 1). At these lower gestational ages, large changes in survival occurred with each additional week of gestational age. At 22 weeks’, except for the Swedish study (36) that reported a survival of 13% in the north and 6% in the south of Sweden, most other studies reported a survival of 0% to 3%. At 23 weeks’, survival ranged between 0% and 41%; at 24 weeks’, between 16% and 70%; and at 25 weeks’, survival ranged between 44% and 85%. Survival was consistently highest in northern Sweden at each gestational age, likely a reflection of proactive management.
|Author||Year of Birth||Study Population||Demoninator||Gestation (wk)||Cohort ≤25 wk||22 wk||23 wk||24 wk||25 wk|
|Total n||Survived (%)||n||Survived (%)||n||Survived (%)||n||Survived (%)||n||Survived (%)|
|Vanhaesebrouck (30)||1999–2000||Population (Belgium)||Livebirths||≤25||175||70 (40)||2||0 (0)||18||1 (6)||65||19 (29)||90||50 (56)|
|Larroque (41)||1997||Population (France)||Livebirths||22 to 25||207||72 (35)||16||0 (0)||30||0 (0)||42||13 (31)||119||59 (50)|
|Hakansson (36)||1995–1999||Population (Sweden, N)||Livebirths||22 to 25||117||123 (69)||8||1 (13)||34||14 (41)||46||32 (70)||89||76 (85)|
|(Sweden, S)||320||154 (48)||18||1 (6)||44||7 (16)||77||38 (49)||181||108 (60)|
|Kamper (31)||1994–1995||Population||Livebirths||≤25||182||54 (30)||(<24 wk) 37||0 (0)||55||9 (16)||90||45 (50)|
|(Denmark)||Actively treated||119||54 (45)||6||0 (0)||35||9 (26)||78||45 (58)|
|Wood (10)||1995||Population (UK, Ireland)||Livebirths||20 to 25||1,185||314 (26)||138||2 (1)||241||26 (11)||382||100 (26)||424||186 (44)|
|Draper (32)||1994–1997||Population (UK)||Live +||≤25||European||(2)||(6)||(16)||(33)|
|Tommiska (33)||1996–1997||Population (Finland)||Livebirths||22 to 25||152||57 (38)||(≤23 wk) 57||5 (9)||(24–25 wk)||95||52 (55)|
|Chan (14)||1996–1997||Multicenter||Inborn||≤25||797||338 (42)||103||1 (1)||150||26 (17)||242||106 (44)||302||205 (68)|
|(Canada)||NICU (In/Outborn)||749||465 (62)||28||4 (14)||109||44 (40)||254||145 (57)||358||272 (76)|
|Lemons (34)||1995–1996||Multicenter(NICHD)||Livebirths (Inborn)||22 to 25||952||511 (54)#||56||12 (21)||216||65 (30)||301||150 (50)#||379||284 (75)#|
|Fanaroff (13)||1999–2000||Multicenter (NICHD)||Livebirths||(≤23 wk) (30)||(59)||(72)|
|El-Metwally (42)||1993–1997||Single center (US)||Livebirths||22 to 25||211||127 (60)||22||1 (5)||41||19 (46)||61||36 (59)||87||71 (82)|
|Hoekstra (43)||1996–2000||Single center (US)||Livebirths||23 to 25||265||212 (80)||—||—||53||35 (66)||97||79 (81)||115||98 (85)|
|McElrath (44)||1995–1999||Single center(US)||Livebirths||23||33||11 (33)||33||11 (33)|
|Cust (45)||1998–1999||Population (NZ)||Livebirths||≤25||167||114 (68)||—||—||(<24 wk) (19)||8 (42)||(24 to 25 wk)||148||106 (72)|
↵# Extrapolated data; Blank spaces indicate data were not provided.
Hakansson (36): North (N) and South (S) Sweden; Survival to 1 year
NICHD=National Institute of Child Health and Human Development; Population=population-based studies; NICU=neonatal intensive care unit.
As mentioned earlier, survival is higher in single-institution or multicenter studies, which generally include only those infants admitted to the NICU. At 22 weeks’ gestation, survival ranged between 1% and 21%; at 23 weeks’, between 17% and 66%; at 24 weeks’, between 44% and 81%; and at 25 weeks’, between 68% and 85%.
Survival by Birthweight
Infants Weighing More Than 500 g
Survival for infants weighing 500 to 749 g (or 800 g) ranged from 55% to 62% (Table 2). Survival improved for each 100-g gain in birthweight. Survival was 29% to 48% for 501 to 600 g, 56% to 63% for 601 to 700 g, and 74% to 84% for 701 to 800 g.
|Author||Year of Birth||Study Population||Denominator||Birthweight (g)||n||Survived (%)||501 to 600 g||601 to 700 g||701 to 800 g|
|n||Survived (%)||n||Survived (%)||n||Survived (%)|
|Warner (37)||1995–1997||Population (US)||Livebirths||500 to 749||170||95 (56)|
|Lemons (34)||1995–1996||Multicentre (NICHD)||Livebirths||501 to 800||1204||700 (58)#||317||92 (29)||449||283 (63)#||439||325 (74)#|
|Fanaroff (13)||1999–2000||Multicentre (NICHD)||Livebirths||501 to 750||1254||690 (55)||(39)||(59)||(77)|
|Lee (15)||1996–1997||Multicentre (Canada)||NICU admission||<750||744||461 (62)|
|Sweet (46)||1994–1998||Single centre (US)||Livebirths||≤600||104||24 (23)|
|Doyle (35)||1997||Population (Australia)||Livebirths||500–749||108||66 (61)||(48)#||(56)#||(84)#|
↵# Extrapolated data; Blank spaces indicate data were not provided.
Population=population-based studies; NICU=neonatal intensive care unit; NICHD=National Institute of Child Health and Human Development; Birthweight categories (35): 500 to 599 g, 600 to 699 g, 700 to 799 g; Survival to 2 years corrected age
Infants Weighing 500 g or Less
A few recent studies have examined survival of infants whose birthweights are 500 g or less (Table 3). The largest international cohort from the Vermont Oxford Network of more than 4,000 infants with birthweights of 401 to 500 g revealed a survival rate of 17%. (39) The survival from an earlier NICHD study of infants of similar birthweight was 11%. (34)
|Author||Year of Birth||Study Population||Denominator||Birthweight (g)||n||Survived (%)|
|Darlow (38)||1998–1999||Population (New Zealand)||NICU admission||<500||13||5 (38)|
|Lucey (39)||1996–2000||Multicentre (VON)||Livebirths||401 to 500||4,172||690 (17)|
|Lemons (34)||1995–1996||Multicentre (NICHD)||Livebirths||401 to 500||195||21 (11)|
|Lee (15)||1996–1997||Multicentre (Canada)||NICU admission||<500||(31)|
Repeated by birthweight and gestational age in tables (13, 34).
VON=Vermont Oxford Network (International); NICHD=National Institute of Child Health and Human Development; NICU=neonatal intentive care unit; Blank spaces indicate data not provided
Proactive Versus Selective Neonatal Care
Hakansson and associates (36) compared survival and major neonatal morbidity in two population-based areas in Sweden related to different management strategies (proactive in the north and selective in the South). For infants at a gestational age of 22 to 25 weeks, the proactive policy, with more centralized management, was associated with more livebirths, fewer deaths within the first 24 hours after birth, and increased survival at 1 year, and there was no increase in neonatal morbidity. Lorenz (47) pointed out that with proactive care, this interesting uncontrolled “experiment” not only will result in a greater absolute number of survivors, but likely will be associated with a corresponding increase in the absolute number of survivors who have disability. In contrast, the selective policy will result in a lower survival rate and fewer survivors who have disability, but at a cost of the death of some infants who would have survived without disability. In a comparison of the differences in management strategies between the selective approach in the Netherlands and the more interventionist practices in the United States for infants between 24 to 26 weeks gestational age, the latter strategy improved survival by 24 infants/100 livebirths, increased disability by 7 cases of cerebral palsy (per 100 livebirths), and at a financial cost of 1,400 ventilator days (per 100 livebirths). (48)
The three most commonly reported morbidities and the ones that appear to have the most significant impact on long-term outcomes are: chronic lung disease (CLD), severe intraventricular hemorrhage (IVH)/periventricular leukomalacia (PVL), and severe retinopathy of prematurity (ROP). Because of varying criteria for defining “severe” and for reporting of CLD/IVH, only general ranges can be provided. CLD was the most prevalent morbidity in the infants, ranging from 13% to 74% among survivors born at 25 weeks’ or less gestation, and from 86% to 100% for infants born at 23 weeks’ or less gestation (Table 4). (44)(49) Depending on the definition, the reported rates for grade 3/4 IVH/PVL ranged from 17% to 21%, and up to 42% for those of 23 weeks’ or less gestation. (42) Assuming most centers were using the International Classification of ROP, the prevalence of stage 3/4 ROP was 14% to 32%. About one third of survivors born at 25 weeks’ or less gestation (23% to 41%) were free of major neonatal morbidities.
|Author||Year of Birth||Study Population||Denominator||≤25 wk|
|CLD n (%)||CNS n (%)||ROP n (%)||No Morbidity* n (%)|
|Costeloe (49)||1995||Population (UK, Ireland)||Survivors||231/314 (74)||52/314 (17)||45/309 (15)||119/314 (38)|
|Cust (45)||1998–1999||Population (New Zealand)||All infants||50/113 (44)||26/153 (17)||15/107 (14)||43/167 (26)|
|Vanhaesebrouck (30)||1999–2000||Population (Belgium)||Survivors||—||—||—||21/70 (30)|
|Serenius (50)||1996–1998||2 centers (Sweden)||Survivors||16/55 (29)||22/54 (41)|
|Chan (14)||1996–1997||Multicenter (Canada)||NICU survivors||(51)||(19)||(32)||(23)|
|Kamper (31)||1994–1995||Population (Denmark)||Survivors||7/54 (13)||10/54 (19)||8/54 (15)|
|El-Metwally (42)||1993–1997||Single center (US)||Survivors||45/123 (37)||27/127 (21)||27/127 (21)|
CLD=chronic lung disease (oxygen dependency at 36 weeks corrected age), CNS=central nervous system disease (parenchymal cysts or ventriculomegaly) (49); Grade 3/4 intraventricular hemorrhage (IVH) (14, 45); Grade 3/4 IVH/periventricular leukomalacia (31, 42); ROP=retinopathy of prematurity: treated ROP (49); Stage ≥3 ROP (14, 42, 45, 50); Stage >2 ROP (31);
↵* Survival without major morbidity: CLD, CNS, ROP (49); CLD, CNS, ROP, necrotizing enterocolitis (NEC) (14, 45, 50); CLD, CNS, ROP, NEC, gut perforation, duct ligation (30).
The Vermont Oxford Network experience with infants weighing 401 to 500 g at birth revealed high rates of CLD (74%) and stage 3/4 ROP (40%) among the survivors, but the prevalence of grade 3/4 IVH was only 8%. (39) For infants who weighed 750 g or less, the prevalence of CLD ranged from 35% to 54% and grade 3/4 IVH from 6% to 19%, with 37% surviving without major neonatal morbidity. (13)(15)(34)
There are fewer reports of neurodevelopmental follow-up of current survivors (Table 5). It also is more difficult to compare and compile the disability rates because of differences in age at assessment and varying criteria for defining and reporting disabilities. Definitions of cerebral palsy, motor impairment, cognitive delay, visual and hearing impairments, and severity of disability varied markedly. In addition, the denominators used for calculating impairments differed from all livebirths, all survivors, NICU admissions, and only those infants who were followed.
|Author||Year of Birth||Study Population||Denominator||Gestation (wk)||Follow-up (%)||Age Assessed (CA, mo)||Outcome||Cohort||≤23 wk n (%)||24 wk n (%)||25 wk n (%)|
|Wood (10)||1995||Population (UK, Ireland)||Followed up||20 to 25||283/308 (92)||30||—DQ<3 SD||53/283 (19)||7/26 (27)||17/90 (19)||29/167 (17)|
|—Severe neuromotor||28/283 (10)||2/26 (8)||11/90 (12)||15/167 (9)|
|—Severe hearing, vision, or communication||25/283 (9)||3/26 (12)||10/90 (11)||123/167 (7)|
|—Severe disability||73/283 (26)||9/26 (35)||24/90 (27)||40/167 (24)|
|Tommiska(51)||1996–1997||Population (Finland)||Followed up||≤25||57/57 (100)#||18||—CP||1/5 (20)||2/18 (11)||4/34 (12)|
|—All motor impairments||1/5 (20)||5/18 (28)||9/33 (27)|
|Kamper (31)||1994–1995||Population (Denmark)||Followed up||≤25||53/54 (98)||24||—CP||No survivors||(24 to 25 wk)||5/53 (9)|
|—Impaired hearing requiring aid||0/53 (0)|
|—Psychomotor retardation||9/50 (18)|
|—No impairment||39/53 (74)|
↵# Extrapolated data
CA=corrected age; DQ (10)=Developmental Quotient; SD=standard deviation; CP=cerebral palsy
Severe neuromotor (10)=unable to walk without assistance, unable to sit, unable to use hands to feed self, unable to control head movement without support or no head control
Severe hearing, vision, or communication (10)=blind or perceives light only, hearing impaired (uncorrected even with hearing aid), communicating by method only or not communicating by systemized speech or other method
Severe disability (10)=one that is likely to put a child in need of physical assistance to perform daily activities
No impairment (31)=Normally developed (ie, without CP, epilepsy, impaired vision or hearing, psychomotor retardation and with Scheffzek score ≤1 [measure of degree of handicap])
The key impairments reported by most investigators were cerebral palsy, blindness, deafness, and cognitive deficits. Many infants, however, had significant developmental lags without a defined impairment. In fact, subnormal cognitive deficits and developmental lags are more prevalent than neurologic impairment, such as cerebral palsy. In a small, single-center study of infants whose birthweights were 600 g or less at 24 months corrected age, 76% of survivors had cerebral palsy, 38% had blindness, and 75% had MDIs less than 70. (46) By gestational age, the prevalence of cerebral palsy was 20% for 23 weeks’ and less, 11% for 24 weeks’, and 12% for 25 weeks’.
Although survival for infants of 401 to 1,000 g birthweight (11) was double for the NICHD study compared with the study by Wood and associates (10) for infants born before 25 weeks’ gestational age, survival without disability was similar at one in two survivors. Overall, severe disability was present in 25% of the survivors, and the same proportion had more than one disability. Boys were more likely to have cerebral palsy than were girls. The mean MDI/Psychomotor Development Index scores on the Bayley Scales of Infant Development II did not vary significantly by gestational age and were in the range of 84 to 87 (1 standard deviation [SD] below mean). Severe cognitive deficit was defined as less than 3 SDs in the study by Wood and associates (10) and was 27% at 23 weeks’ gestation and younger and 17% to 19% at 24 to 25 weeks’ gestation. The proportion of infants who had moderate cognitive deficits (2 SDs to 3 SDs below the mean) was 11% to 13%. (10)
Morbidity for Infants Weighing Less Than 500 g at Birth
In a passionate commentary, Lucey (52) expressed concerns about the aggressive prenatal and postnatal management of “fetal infants” without clear knowledge of the appropriate therapies, nutritional needs, and long-term outcomes. He asked whether such management makes sense, suggesting that because of the bleak outlook for intact survival of these infants, we should conduct a trial in which neonatal intensive care is randomized and survivors are followed for 10 to 15 years.
Prediction of Outcome
Schmidt and colleagues (53) presented a simple model for predicting adverse outcome at 18 months (defined as death or the presence of cerebral palsy, cognitive delay, hearing impairment requiring amplification, or bilateral blindness) using a count of three neonatal morbidities (CLD, ultrasonographic evidence of brain injury, and severe ROP). Each of the risk factors similarly and independently correlated with a poor outcome. In the absence of any of the risk factors, the rate of adverse outcome was 18% (95% confidence interval [CI], 14% to 22%); the presence of one, two, or all three of the risk factors corresponded to rates of 42% (95% CI, 37% to 47%), 62% (95% CI, 53% to 70%), and 88% (95% CI, 64% to 99%), respectively.
Despite recent advances in perinatal and neonatal care, infants born at fewer than 26 weeks gestational age continue to contribute disproportionately to perinatal mortality and subsequent disabilities. This review is based on infants born since the mid-1990s. Although there is considerable information in the literature on current survival and neonatal morbidity, it is not accompanied by studies on longer-term neurodevelopmental outcomes. It is clear that such studies require considerable resources, commitment, and compliance by both health professionals and funding agencies. Despite repeated pleas by several investigators, it appears that support for such investigation is not given the priority it deserves. Ideally, when counseling parents about prognosis, the outcomes should be based on survivors born no more than 5 years earlier, (40) but realistically, it takes a few more years to publish such data. It is, therefore, vital to continue the follow-up of the most current survivors to provide updated reports not only to neonatologists, but also to obstetricians who are first in line for offering or withholding interventions. (4)
- Copyright © 2005 by the American Academy of Pediatrics
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