Studies have shown that lactation is associated with a loss of bone density from four to seven percent at the spine and hip among women who lactate for six months. Decline in bone density with lactation occurs rapidly. Although bone density increases after weaning, there is controversy on whether or not it is completely restored. Epidemiological studies find no significant negative impact of lactation on bone mass or fractures, and in fact there is evidence that lactation has a positive effect on bone mass. We think that interventions that attenuate this physiologic loss of bone that is associated with lactation and accelerate restoration of bone mass after weaning may result in improved long term bone mass and diminished fracture risk.