Heidi Kalkwarf, PhD, RD, Associate Professor of Pediatrics at Cincinnati Children's Hospital Medical Center et al., wrote in their paper "Milk Intake During Childhood and Adolescence, Adult Bone Density, and Osteoporotic Fractures in U.S. Women," published Jan. 2003 in the American Journal of the College of Nutrition:

“We found that low milk intake during childhood and adolescence was associated with low[er] BMC [bone mineral content] or BMD [bone mineral density] of the hip in adulthood… in women who reported consuming <1 serving of milk/week than in women who consumed >1 serving/day during childhood and adolescence. This presumably represents a persistent negative effect of low milk intake during growth on bone mass and density of the hip that is not completely ameliorated by current calcium or milk intake. Furthermore, among women 50 years of age or older, those with low milk intake during childhood had a 2-fold greater risk of fracture than did women with high milk intake during childhood…

We found that milk intake in childhood and adolescence is associated with increased bone mass and density in adulthood, and this effect is independent of current milk or calcium intake. These findings support efforts to promote a diet containing one or more servings of milk/d for girls during childhood and adolescence to increase bone mass and density in adulthood and reduce the risk of osteoporotic fracture.”

Jan. 2003