I am not expert with this question and would hope someone who has done
     research in bone growth during and after lactation could help answer
     your questions. I do believe that lactation does affect bone growth--
     both positively and negatively, depending on the stage of lactation.
     Bone growth is somewhat dependent upon hormonal as well as dietary
     influences, and, if I remember correctly, the bone density changes
     during lactation as well as after lactation stops.  Sometime after
     lactation is stopped -- I'm thinking 6 to 7 months later, the bone
     density can actually be greater than before lactation begins.  This is
     one reason lactation is thought to have some protection against
     osteoporosis. Hope this helps.