IGF-I and IGFBP-3 in healthy 9 month old infants from the SKOT cohort: Breastfeeding, diet, and later obesity

Abstract

BackgroundHigh IGF-I concentrations in infancy have been associated with later obesity but the interactions between diet, IGF-I concentrations and growth in early life are complex and involve programming of the IGF-I axis. ObjectiveThis paper examines how IGF-I and IGFBP-3 concentrations measured at age 9months are related to diet and growth in infancy. DesignIn the Danish SKOT cohort healthy term infants were included at age 9months with follow-up at age 18months. Total 252 infants had a full data set and were included in the analysis. Measurements include weight, length, skinfold thickness, waist circumference, 7-d food records, and blood analysis of IGF-I, and IGFBP-3. ResultsInfants not being breastfed at 9months of age (46%) had higher median IGF-I concentration than breastfed infants (51.6 vs. 44.2ng/mL, P=0.0005) and there was a negative dose response effect of daily numbers of breastfeedings on IGF-I concentration. IGF-I concentration was negatively associated with birth weight and positively related to increase in weight, length and BMI between birth and 9months. Between 9months and 18months of age increase in length was positively and increase in BMI was negatively related to IGF-I concentration. ConclusionBreastfeeding has a strong negative effect on IGF-I concentrations in late infancy. Although IGF-I concentrations at 9months of age were negatively associated with change in BMI during the following 9months we speculate that this could reflect an early adiposity rebound and thereby an increased risk of obesity later in life.