Late introduction of complementary feeding, rather than duration of breastfeeding, may protect against adult overweight.

BACKGROUND Early nutrition may affect the risk of overweight in later life. OBJECTIVE The objective was to explore the effect of the duration of breastfeeding (BF) and age at introduction of complementary feeding (CF) on body mass index (BMI) during childhood through adulthood. DESIGN The study was based on a subsample of the Copenhagen Perinatal Cohort established in 1959-1961 (n = 5068). Information on BF and available information on CF (age of introduction of "spoon-feeding," "vegetables," "egg," "meat," and "firm food") and several covariates were collected in infancy and linked with information on BMI from follow-up examinations in childhood and adulthood at age 42 y. RESULTS The median (10th, 90th percentiles) durations of any BF and age at introduction of spoon-feeding were 2.50 (0.23, 6.50) and 3.50 (2.00, 6.00) mo, respectively. After 1 y of age and throughout childhood and adolescence, no association between BF and BMI was found in regression models also adjusted for age at introduction of spoon-feeding and covariates. The risk of overweight at age 42 y decreased or tended to decrease with increasing age (in mo) at introduction of spoon-feeding [odds ratio (OR): 0.94; 95% CI: 0.86, 1.02], vegetables (OR: 0.90; 95% CI: 0.81, 0.98), meat (OR: 0.93; 95% CI: 0.87, 1.00), and firm food (OR: 0.92; 95% CI: 0.86, 0.98) but not egg (OR: 0.98; 95% CI: 0.91, 1.05). CONCLUSION The findings of this study suggest that introduction of CF at a later age (within the range of 2 to 6 mo) is protective against overweight in adulthood but do not support a protective effect of a longer duration of BF.