A cohort study results showed that infants who received resuscitation have an increased risk for low intelligence-quotient (IQ) scores when they reach 8 years of age. This was proved in children who subsequently developed encephalopathy but also for those who were apparently healthy after resuscitation. The author David E. Odd, MD, from the University of Bristol, in the United Kingdom noted that the findings are consistent with a cerebral injury of sufficient severity to delay respiration but insufficient to cause obvious symptoms of encephalopathy. They also noted that if the relationship between resuscitation without encephalopathy and low IQ is causal then it could account for about 1 in 30 adults who have a low IQ, which is a larger proportion than is attributable to the infants who developed encephalopathy. Death or neurological deficit may occur due to severe perinatal cerebral-injury, however the theory of a continuum of reproductive casualty suggests that mild perinatal events might also have an effect on cognitive function that are subtler and therefore not detectable until later in life. The researchers conducted study on 3 groups of infants from the Avon Longitudinal Study of Infants and Children: 815 infants who were resuscitated but who showed no symptoms of encephalopathy as a consequence; 58 infants who were resuscitated and required neonatal care for symptoms of encephalopathy; and 10,609 who were not resuscitated and did not show symptoms of encephalopathy as a reference group. Cognitive function was then assessed at a mean age of 8.6 years. A score of less than 80 was considered a low IQ. IQ scores were ultimately available for 5887 of the children, and the results were adjusted for a number of clinical and social covariates. In the main analysis, the researchers found an increased risk for low IQ among resuscitated infants both with and without symptoms of encephalopathy. However, it was noted that the population of asymptomatic infants was larger than that of infants with encephalopathy, and therefore the population-attributable risk fraction for an IQ score that might be attributable to the need for resuscitation at birth was 3.4% (95% CI, 0.5 – 6.3) for asymptomatic infants and 1.2% (95% CI, 0.2 – 2.2) for those who developed encephalopathy. Authors concluded that the data suggest that mild perinatal physiological compromise might be sufficient to cause subtle neuronal or synaptic damage and thereby affect cognition in childhood and potentially adulthood. Among limitations of the study findings, though, is a change in practice since these children were born in the use of 100% oxygen in resuscitation equipment, which has subsequently been shown to be associated with worse outcomes than normal room air, so it is noted that their finding might not be applicable to infants born in the present day. By saying that their findings still support the concept of a continuum of reproductive casualty, they concluded that education and training interventions targeted at obstetric and neonatal staff improve measures of birth condition, and the identified association could have important population benefits if it is shown to be causal.