Of the seven confirmed birth weight loci, five had previously been associated with either type 2 diabetes (CDKAL1 and ADCY5), blood pressure (ADRB1) or adult height (LCORL and HMGA2). To assess whether association with birth weight is a common feature of loci associated with these adult traits, we extracted results from our Stage 1 discovery meta-analysis for 49 published type 2 diabetes SNPs7,22,35-48, 180 height SNPs21 and 30 blood pressure SNPs14,17. To complement these analyses, we analyzed the associations between the same sets of SNPs and birth weight z score in n = 5,327 mother-child pairs from the ALSPAC study. We adjusted for sex and gestational age, recorded the results before and after adjustment for maternal genotype and compared the fit of the two models using a likelihood ratio test to assess evidence of confounding by maternal genotype. This was particularly important for the analyses of type 2 diabetes SNPs since there is evidence that at least two of the known loci influence birth weight via the maternal genotype49,50. For each set of loci, we used the binomial probability (sign)
