Maternal-Fetal Interactions and Birth Order Inf luence Insulin Variable Number of Tandem Repeats Allele Class Associations with Head Size at Birth and Childhood Weight Gain

Polymorphism of the insulin gene (INS) variable num-ber of tandem repeats (VNTR; class I or class III alleles) locus has been associated with adult diseases and with birth size. Therefore, this variant is a potential contrib-utory factor to the reported fetal origins of adult dis-ease. In the population-based Avon Longitudinal Study of Pregnancy and Childhood birth cohort, we have con-firmed in the present study the association between the INS VNTR III/III genotype and larger head circumfer-ence at birth (odds ratio [OR] 1.92, 95 % CI 1.23–3.07; P 0.004) and identified an association with higher cord blood IGF-II levels (P 0.05 to 0.0001). The genotype association with head circumference was in-fluenced by maternal parity (birth order): the III/III OR for larger head circumference was stronger in secon