Background/objectives:Previous studies have suggested that milk consumption during pregnancy may have growth-promoting effects on the offspring in utero. Whether this effect tracks beyond the prenatal period remains unclear. We examined whether milk consumption during pregnancy is associated with infant size at birth and offspring's height-and growth-related biomarkers at ∼20 years of age.Subject/methods:A prospective cohort of 809 Danish pregnant women was recruited in 1988-1989, with offspring follow-up at ∼20 years of age (n=685). Milk consumption was assessed at gestational week 30 using a food frequency questionnaire. Birth weight and birth length were measured according to standard procedures at delivery and converted to specific z-scores, adjusted for gestational age and gender.Results:In adjusted models, maternal milk consumption of ≥150 ml/day vs <150 ml/day was associated with 0.32 higher z-scores for birth weight (95% confidence interval (CI) 0.06; 0.58) and 0.34 higher z-scores for birth length (95% CI 0.04; 0.64). At follow up, ∼20 years later, those offspring whose mothers had consumed ≥150 ml milk/day tended to have 0.19 higher z-scores for height (P=0.16), ∼8% higher levels of insulin-like growth factor I (P=0.12) and ∼14% higher insulin levels (P=0.11) compared with offspring whose mothers consumed <150 ml milk/day.Conclusions:Our findings add to recent observations that maternal milk consumption may have a growth-promoting effect with respect to weight and length at birth. Furthermore, the results provide some suggestion that this effect may even track into early adult age, although further studies with more statistical power are needed for that purpose.