A Cochrane review included 25 studies with a total of 3 615 subjects. There was variability with regard to the focus and intensity of the intervention, subject characteristics and in length of follow-up. Meta-analysis concluded that intervention improved cognitive outcomes at infant age (developmental quotient [DQ]: SMD 0.32, 95% CI 0.16 to 0.47; 16 studies, n=2 372), and at preschool age (intelligence quotient [IQ]; SMD 0.43, 95% CI 0.32 to 0.54; 8 studies, n=1 436). However, this effect was not sustained at school age (IQ; SMD 0.18 SD, 95% CI -0.08 to 0.43; 5 studies, n=1 372). There was significant heterogeneity between studies for cognitive outcomes at infant and school ages.
In regards to motor outcomes, meta-analysis of 12 studies showed a significant effect in favour of early developmental interventions at infancy only; however, the effect was small (motor scale DQ: SMD 0.10, 95% CI 0.01 to 0.19; 12 studies, n=1 895). There was no effect on the rate of cerebral palsy in survivors (RR 0.82, 95% CI 0.52 to 1.27; 7studies, n=985). There was little evidence for a positive effect on motor outcomes in the long term, with only 5 of the included studies reporting outcomes at pre-school or school age.
Comment: The quality of evidence is downgraded by inconsistency (variability in results).