and child underweight.61 GBD estimates for the prevalence of low birthweight and short gestation are slightly lower when compared with WHO estimates, but show similar geographical patterns.62 Scientific literature reveals similar results to GBD for impaired kidney function63 and low birthweight and short gestation;64, 65 research analysing ambient air pollution66 differed from GBD estimates due to older methods and less granularity. Research published on iron-deficiency anaemia67 differs from GBD in methods and definitions, resulting in generally higher GBD estimates. GBD estimates were much lower than published research on occupational estimates,3, 68, 69 largely due to different cause-outcome pairs and GBD's application of the CRA approach (see appendix 1 p 10).
