In inbred and outbred mice, this study examines natural intrauterine growth restriction (IUGR) in relation to body weight, telomere length (TL), glucose tolerance, and growth factor gene (Igf1, Igf2, Insr, Igf1r, and Igf2r) mRNA expression levels in the brain, liver, and muscle at 2- and 10 days of age and then at 3- and 9 months of age. The gene discussed is IGF1R; the disease is fetal growth restriction.