The experiment built upon the methodology employed in our previous studies [6,15,16]. The Cambridge Baby Growth Cohort Study (CBGS) is a UK prospective observational cohort, with longitudinal infancy anthropometric measures and collection of detailed demographics and infant feeding [9]. Mother-infant pairs were recruited from a single maternity unit in Cambridge, UK. Inclusion criteria included singleton, term, and healthy infants with normal birth weight and no significant comorbidities during pregnancy. Infants with a genetic or syndromal disease were excluded from the analyses. Studies were approved by National Research Ethics Service Cambridgeshire 2 Research Ethics Committee (REC) with REC reference 00/325, and all mothers gave informed written consent. This study involved a subgroup of CBGS (total n=201) with available dried capillary blood spots samples. Subjects were recruited between 02/10/2003 and 29/08/2009.