Prenatal and postnatal milk supplementation and adult insulin-like growth factor I: Long-term follow-up of a randomized controlled trial

Objective: Insulin-like growth factors (IGF) are increasingly recognized as important determinants of adult health, in particular risk of certain cancers. However, little is known about the determinants of adult IGFs and to what degree they may be programmed by early life influences. Design: Randomized controlled trial of prenatal and postnatal milk supplementation among 951 subjects born in 1972 to 1974 in South Wales. Main outcome measure: Measures of IGF-I, IGF binding protein 3, and the molar ratio. Results: Data on adult IGFs were available from 663 subjects at a mean age of 25 years. Subjects in the intervention arm had lower IGF-I (-8.5 ng/mL; 95% confidence interval, -15.1 to -1.8, P = 0.01) and ratio (-1.20; 95% confidence interval, -2.33 to -0.04, P = 0.04). These differences could not be explained by follow-up bias or confounding factors. Conclusions: These results provide experimental data on the role of early life programming either in the intrauterine or postnatal period that may have long-term influences on the IGF axis, with potential implications for disease risk.