Subjects were categorized into 2 weight groups: >2000g=”heavier” (N=362)and <2000g=”lighter” (N=623). Random assignment to the intervention or follow-up within each group resulted in 220 heavier infants were assigned to follow-up and 142 to intervention. In the lighter group, 388 were assigned to follow-up and 235 to intervention.

Child Development Centers: Beginning at 12 months and continuing until 36 months, the intervention children attended the center 5 days a week. The teaching staff continued to implement the curriculum of learning activities used by the home visitors and tailored the program to each child’s needs and developmental level. Teacher-child ratios were 1:3 for children aged 12-23 months and 1:4 for those aged 24-36 months; class sizes were 6 and 8 children, respectively. Each site provided transportation.

Parent Groups: Beginning at 12 months, bimonthly parent groups meetings provided information on child rearing, health, and safety, and other parenting concerns, as well as some degree of social support.

Overall Morbidity Measure (Verbatim reports assigned International Classification of Diseases ICD-Ninth Revision codes. In addition, children were tested for cerebral palsy at age 3 years based on medical examination);

Morbidity Index (Index is a summation over the three years of the number of hospitalizations, outpatient surgeries, injuries not resulting in hospitalization or outpatient surgery, and different (code) illnesses and conditions);

Serious Morbidity Index (Index consists of the number of years (0-3) in which there was one or more of the following: hospitalizations, outpatient surgeries, prolonged or recurrent illnesses totaling 30 days or longer in a given year, and injuries or briefer illnesses that were predefined as serious by a panel of physicians);

Maternal Perception of Child Health Status: General Health Rating Index (Index from Rand Corporation Health Insurance Study. All health data were collected by clinic staff, except the 36-month growth measures);

Functional Status II(R)Scale (Growth was assessed by length and body mass index at 36 months)

“At corrected age 36 months, the intervention group had significantly higher mean IQ scores than the follow-up group (mean difference in the heavier group was 13.2 and in the lighter group 6.6), significantly fewer maternally reported behavior problems, and a small, but statistically significant, increase in maternally reported minor illnesses for the lighter-birth-weight group only, with no difference in serious health conditions.”

“Cognitive development scores were 7.2 points higher (p=0.002) in the intervention (INT) group, after adjustment for baseline differences in site, sociodemographic characteristics, and neonatal morbidity, and were 9.4 points higher (p<0.003) when the 29 children with significant cerebral palsy were removed. No differences in behavior, serious morbidity, functional status, or health rating were found overall. The infants in the INT group who weighed <1000 grams at birth had significantly lower behavior problem scores but no differences on other outcomes. All children in the INT group had slightly higher rates of less serious morbidity.”

“At age 5 years, the intervention group had full-scale IQ scores similar to children in the follow-up only group. However, in the heavier LBW stratum, children in the intervention group had higher full-scale IQ scores (3.7 points higher; p=.03) and higher verbal IQ scores (4.2 points higher; p=.02). No significant differences between intervention and follow-up only groups in cognitive measures at age 5 years were noted in the lighter LBW infants. The intervention and follow-up groups were similar in behavior and health measures regardless of LBW stratum.”

“At age 8 years, in the entire cohort and in the lighter LBW stratum, the intervention and follow-up only groups were similar on all primary outcomes measures. Differences favoring the intervention group were found within the heavier LBW group: full-scale IQ score (4.4 points higher; p=.007), verbal IQ score (4.2 points higher; p=.01), performance IQ score (3.9 points higher; p=.02), mathematics achievement score (4.8 points higher; p=.04), and receptive vocabulary score (6.7 points higher; p=.001). On a physical functioning subscale, the whole intervention group received less favorable ratings, while the lighter LBW intervention group had lower maternal ratings assessing social limitations caused by behavior.”

“Second, assessments need to be refined enough to detect qualitative differences between heavier and lighter LBW infants. For example, maternal reports of attention deficit or distractibility may reflect environmental conditions for the heavier LBW child but may be related to neurological impairment in the lighter LBW child. The heavier LBW child may respond to changes in environment that the mother can control, but the lighter LBW child may need a more structured and professionally designed situation”(131).

“Third, the lack of sustained effect may reflect the need for different or continued support of lighter LBW children. It is the task of future research to characterize the populations needing ongoing support; to explore the type, intensity, and duration of interventions needed to produce sustained effects; and to develop policies to implement such interventions. Finally, the corresponding low mean IQ scores and high rates of school failure of LBW children underscore the importance of public health efforts to reduce premature births”(131).