Early Childhood Neurodevelopmental Outcomes of High-Risk Neonates

Advances in obstetric and neonatal care, which have been responsible for the improved survival of high-risk neonates, have not resulted in decreased morbidity. Since perinatal interventions can alter later growth and development, long-term follow-up is essential to ensure therapies such as oxygen administration and postnatal steroids, which demonstrate dramatic and immediate positive effects, are not associated with adverse long-term outcomes. The earliest follow-up studies of preterm infants after the introduction of modern methods of neonatal intensive care in the 1960s described a decrease in adverse neurodevelopmental sequelae compared with that of the preceding era. During the 1980s and 1990s, there was a continued decrease in mortality, and thus the absolute number of both healthy and neurologically impaired survivors increased. Furthermore, the survival of increasing numbers of extremely immature infants with low birth weight resulted in a relatively high disability rate in the subpopulation of infants born weighing less than 750 g or born at less than 26 weeks’ gestation. Since 2000, mortality rates for infants with very low birth weight have leveled off. Several studies suggest declining rates of major neurodevelopmental impairment, including cerebral palsy. As the initial survivors of neonatal intensive care have reached young adulthood, a myriad of more subtle neurodevelopmental issues such as visuomotor problems, learning disabilities, autism, or developmental coordination disability have flooded the literature. Additionally, the survival of increasingly immature infants along with improvements in managed care systems have resulted in early discharge of infants with unresolved medical or surgical issues such as oxygen dependence, need for assisted ventilation, maintenance of external medical devices, or dependence on gastrostomy feeds.

Infants at highest risk for later neurodevelopmental problems resulting from perinatal sequelae include those who had severe asphyxia, severe intracranial hemorrhage, infarction or periventricular leukomalacia, meningitis, seizures, respiratory failure resulting from pneumonia, persistent fetal circulation, or bronchopulmonary dysplasia, and multisystem congenital malformations, as well as children born with extremely low birth weight or at extremely early gestational age ( Boxes 60.1 and 60.2 ). The rates of health problems and neurodevelopmental sequelae are inversely proportional to both birth weight and gestational age ( Fig. 60.1 and Table 60.1 ).

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Percentage of 8-year-old children born very preterm between 24 and 32 weeks’ gestation from 1997-1998 with major impairments.

(Data from Marret S, et al. Brain injury in very preterm children and neurosensory and cognitive disabilities during childhood: the EPIPAGE cohort study. PLoS ONE 8 (5): e62683. doi:10.1371/journal.pone.0062683.)

Although most survivors of prematurity are not significantly impaired, there are a variety of medical and neurodevelopmental sequelae that necessitate scrutiny. Therefore, follow-up programs should be an integral extension of every neonatal intensive care unit. The goals of effective follow-up programs include early identification of neurosensory or developmental disability, parental counseling, identification and treatment of medical complications, identification of risk factors for impairment, evaluation of the impact of therapeutic interventions, and provision of feedback for perinatal and pediatric caregivers. In particular, specialized follow-up care must consider problems of growth, development, behavior, and chronic disease. If possible, follow-up care should initially involve the coordinated and complementary effort of the neonatologist and the primary care pediatrician. If there are concerns for developmental or neurologic problems, the child should also be referred to a subspecialist or a child development center.

The initial continuity of care by the neonatologist is important to reassure the family that the same personnel responsible for the life-saving decisions are continuing to assume responsibility for the child's adaptation into home life. Neonatal care providers also benefit from involvement in follow-up care by maintaining contact with infants leaving the nursery and observing the long-term consequences of prematurity and neonatal morbidities. Growth (weight, height, and head circumference), neurologic development, psychomotor and cognitive development, vision, and hearing all should be longitudinally assessed within follow-up. Transitioning care of these infants to the general pediatrician gradually may greatly benefit the patient, the family, and the pediatrician as trust and familiarity are developed.

In planning neonatal follow-up programs, various models of care are possible but may be constrained by available resources. A minimal requirement for the clinical monitoring of outcomes is a periodic assessment of growth and neurosensory development during the first 2 years of life. The ideal is a comprehensive program involving all aspects of care, including well-baby care, evaluation of outcome, social and educational intervention, and therapy when needed. A home nurse visiting program, especially during the early postdischarge period, and parent support groups for selected high-risk conditions (e.g., children with chronic lung disease) also should be considered. There is evidence that educational enrichment during infancy and early childhood might improve the early childhood outcome of high-risk and preterm infants, especially those from socioeconomically deprived groups. The lack of hypothesis-driven trials of early developmental intervention has resulted in little evidence of sustained improvement in school-age neurodevelopmental outcomes.

Outcomes from different centers are heavily influenced by the demographic and socioeconomic profile of the parents, the regional incidence of extreme prematurity, the percentage of inborn patients at a given center, a selective treatment or admission policy, site-specific practice patterns, and the rate of follow-up. Intercenter differences in neonatal sequelae and outcome are well described. Regional results, rather than national or international cohort data, may therefore reflect a more accurate picture of outcome, because they include all infants born in an area. This is the ideal situation, but such studies are rarely available in the United States. Individual centers should be aware of their own patients’ social risk factors and rates of neonatal morbidity and, if possible, maintain their own follow-up outcome data.

Any evaluation of the outcome studies of high-risk infants must include the population status (inborn, outborn, or regional) and the choice of a comparison group that includes either a normal birth weight group or infants within a similar birth weight or gestational age range who do not have the condition or therapy under study. It also is essential to control for sociodemographic factors, such as maternal marital status, ethnicity, and education, and to consider possible genetic factors when evaluating cognitive outcome or school performance.

Consideration of neonatal mortality is important for judging the aggressiveness and level of neonatal care, which might influence the quality of outcome of the survivors. Other factors to be considered are the rate of loss of infants to follow-up, the neonatal and postdischarge death rate, the age at follow-up, and the method of follow-up. Two years is the earliest age to get a fairly reliable assessment of neurodevelopmental outcome. At age 4-5 years, cognitive function and language can be better measured, and follow-up at age 7-9 years allows an assessment of subtle neurologic and behavioral dysfunction and school academic performance ( Fig. 60.2 ).

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Rates of school problems among 8-year-old very preterm versus term-born children.

(Data from Larroque B, et al. Special care and school difficulties in 8-year-old very preterm children: the EPIPAGE cohort study. PLoS One. 2011;6(7):e21361.)

Because it is impossible to provide ongoing high-risk follow-up care for all infants treated in the neonatal intensive care unit, specific criteria have been proposed to identify children at greatest risk for sequelae. Traditionally, follow-up programs primarily targeted children with birth weight of less than 1500 g or gestational age of less than 32 weeks. However, therapies such as inhaled nitric oxide and extracorporeal membrane oxygenation have increased the demand for highly specialized follow-up clinics for term infants with persistent pulmonary hypertension, meconium aspiration, and sepsis.

In addition, a growing number of infants with major congenital malformations such as congenital diaphragmatic hernia now survive the neonatal period to require intensive ongoing follow-up support. Centers with active research components could select additional candidates for follow-up in the high-risk clinic on the basis of participation in specific research studies. Because of the significant costs associated with evaluating all eligible follow-up patients in the clinic setting, parent and teacher questionnaires have been suggested. These questionnaires typically provide a checklist of various individual measures of health status and disability ( Box 60.3 ).