Follow up studies: design, organisation, and analysis.

The follow up of infants who were exposed to adverse perinatal events is an important component of perinatal audit. We need to know whether the changes in perinatal care that have undoubtedly resulted in their improved survival have altered the incidence of impairments in their long term health, growth, or neurodevelopmental state. Moreover, recent improvements in diagnostic imaging tech- niques carried out in the neonatal period may con- siderably enhance our ability to predict longer term How can we improve on study design?