A question that arises is whether these disparities in birth weight should be a cause for concern, or rather how much concern. Apart from the higher costs and increased risk of mortality which are associated with infant health, a growing literature has linked birth weight to a number of different outcomes in later life. In other words these inequalities in infant health are likely to persist. I also pursue this with the GUI data, and find that birth weight is predictive of various indicators at age 9, and not just health. The following graph depicts the relationship between Drumcondra maths/reading scores and birth weight. Again, controlling for the rich set of information available in the data does not alter this relationship substantially. Omitted variable bias is still a concern of course, however these results are entirely consistent with the literature, and in this context there is good reason to believe that there is at least some causal component to these effects. For a good review on the health side see the recent paper Almond, D. and J. Currie (2011). "Killing Me Softly: The Fetal Origins Hypothesis." Forthcoming in the The Journal of Economic Perspectives. Numerous twin studies also support this view, for example Black, S. E., P. J. Devereux, et al. (2007) "From the cradle to the labor market? the effect of birth weight on adult outcomes" The Quarterly Journal of Economics 122(1): 409-439.I will be releasing a working paper on this shortly.