Maureen Hack

BACKGROUND: Very-low-birth-weight infants (those weighing less than 1500 g) born during the initial years of neonatal intensive care have now reached young adulthood. METHODS: We compared a cohort of 242 survivors among very-low-birth-weight infants born between 1977 and 1979 (mean birth weight, 1179 g; mean gestational age at birth, 29.7 weeks) with 233 controls from the same population in Cleveland who had normal birth weights. We assessed the level of education, cognitive and academic achievement, and rates of chronic illness and risk-taking behavior at 20 years of age. Outcomes were adjusted for sex and sociodemographic status. RESULTS: Fewer very-low-birth-weight young adults than normal-birth-weight young adults had graduated from high school (74 percent vs. 83 percent, P=0.04). Very-low-birth-weight men, but not women, were significantly less likely than normal-birth-weight controls to be enrolled in postsecondary study (30 percent vs. 53 percent, P=0.002). Very-low-birth-weight participants had a lower mean IQ (87 vs. 92) and lower academic achievement scores (P<0.001 for both comparisons). They had higher rates of neurosensory impairments (10 percent vs. <1 percent, P<0.001) and subnormal height (10 percent vs. 5 percent, P=0.04). The very-low-birth-weight group reported less alcohol and drug use and had lower rates of pregnancy than normal-birth-weight controls; these differences persisted when comparisons were restricted to the participants without neurosensory impairment. CONCLUSIONS: Educational disadvantage associated with very low birth weight persists into early adulthood.

BACKGROUND: Advances in perinatal care have resulted in increased survival rates for extremely low birth weight children. We sought to examine the relative changes in rates of survival and neurodevelopmental impairment at 20 months of corrected age among 500- to 999-g birth weight infants born at our perinatal center during 2 periods, before and after the introduction of surfactant therapy in 1990. METHODS: Four hundred ninety-six infants with birth weights of 500 to 999 g were born at our perinatal center during period I (1982-1989) (mean body weight: 762 g; mean gestational age: 25.8 weeks) and 682 during period II (1990-1998) (mean body weight: 756 g; mean gestational age: 25.5 weeks). Rates of death and survival with and without neurodevelopmental impairment at 20 months of corrected age for the 2 periods were compared with logistic regression analyses, with adjustment for gestational age. RESULTS: Survival rates increased from 49% during period I to 67% during period II. Neonatal morbidity rates also increased during period II, including rates of sepsis (from 37% to 51%), periventricular leukomalacia (from 2% to 7%), and chronic lung disease, defined as oxygen dependence at 36 weeks of corrected age (from 32% to 43%). Rates of severe cranial ultrasound abnormalities were similar (22% vs 22%). Among children monitored, the rate of neurologic abnormalities, including cerebral palsy, increased from 16% during period I to 25% during period II and the rate of deafness increased from 3% to 7%. The overall rate of neurodevelopmental impairment (major neurosensory abnormality and/or Bayley Mental Developmental Index score of <70) increased from 26% to 36%. Compared with period I, in period II there were decreased rates of death (odds ratio [OR]: 0.3; 95% confidence interval [CI]: 0.2-0.4) and increased rates of survival with impairment (OR: 2.3; 95% CI: 1.7-3.3) but also increased rates of survival without impairment (OR: 1.7; 95% CI: 1.3-2.2). Compared with period I, for every 100 infants with birth weights of 500 to 999 g born in period II, 18 additional infants survived, of whom 7 were unimpaired and 11 were impaired. CONCLUSIONS: The improved survival rates in the 1990s occurred with an increased risk of significant neurodevelopmental impairment. Prospective parents of extremely low birth weight infants should be advised of this substantial risk, to facilitate decision-making in the delivery room.

Advances in neonatal medicine have resulted in the increased survival of infants at lower and lower birth weight. While these medical success stories highlight the power of medical technology to save many of the tiniest infants at birth, serious questions remain about how these infants will develop and whether they will have normal, productive lives. Low birth weight children can be born at term or before term and have varying degrees of social and medical risk. Because low birth weight children are not a homogeneous group, they have a broad spectrum of growth, health, and developmental outcomes. While the vast majority of low birth weight children have normal outcomes, as a group they generally have higher rates of subnormal growth, illnesses, and neurodevelopmental problems. These problems increase as the child's birth weight decreases. With the exception of a small minority of low birth weight children with mental retardation and/or cerebral palsy, the developmental sequelae for most low birth weight infants include mild problems in cognition, attention, and neuromotor functioning. Long-term follow-up studies conducted on children born in the 1960s indicated that the adverse consequences of being born low birth weight were still apparent in adolescence. Adverse sociodemographic factors negatively affect developmental outcomes across the continuum of low birth weight and appear to have far greater effects on long-term cognitive outcomes than most of the biological risk factors. In addition, the cognitive defects associated with social or environmental risks become more pronounced as the child ages. Enrichment programs for low birth weight children seem to be most effective for the moderately low birth weight child who comes from a lower socioeconomic group. Continued research and attempts to decrease the rate of low birth weight and associated perinatal medical sequelae are of primary importance. Ongoing documentation of the long-term outcome of low birth weight children needs to be mandated, as does the implementation of environmental enrichment programs to help ameliorate the long-term consequences for infants who are born low birth weight.

BACKGROUND: Since the mid-1980s, increasing numbers of children with birth weights under 750 g have survived to school age. METHODS: We matched a regional cohort of 68 surviving children born from 1982 through 1986 with birth weights under 750 g (mean, 670 g; gestational age, 25.7 weeks) with 65 children weighting 750 to 1499 g at birth and 61 children born at term. Growth, neurosensory status, and functioning at school age in the three groups were compared. Associations of biologic and social risk factors with major developmental outcomes were examined by means of logistic-regression analyses. RESULTS: Children with birth weights under 750 g were inferior to both comparison groups in cognitive ability, psychomotor skills, and academic achievement. They had poorer social skills and adaptive behavior and more behavioral and attention problems. The mean (+/- SD) Mental Processing Composite score for the cohort was 87 +/- 15, as compared with 93 +/- 14 for children with birth weights of 750 to 1499 g and 100 +/- 13 for children born at term (P < 0.001). The rates of mental retardation (IQ < 70) in the three groups were 21, 8, and 2 percent, respectively; the rates of cerebral palsy were 9, 6, and 0 percent; and the rates of severe visual disability were 25, 5, and 2 percent. Major cerebral ultrasonographic abnormalities were associated with mental retardation (odds ratio, 5.4; 95 percent confidence interval, 1.8 to 15.8) and cerebral palsy (odds ratio, 15.2; 95 percent confidence interval, 3.0 to 77.4). Oxygen dependence at 36 weeks was associated with mental retardation (odds ratio, 4.5; 95 percent confidence interval, 1.2 to 10.7) and severe visual disability (odds ratio, 4.3; 95 percent confidence interval, 1.3 to 14.2). Social disadvantage, though associated with several neuropsychological outcomes, was not associated with major developmental impairment. CONCLUSIONS: Children with birth weights under 750 g who survive represent a subgroup of very-low-birth-weight children who are at high risk for neurobehavioral dysfunction and poor school performance.