I dont know if where your baby chooses to implant in the uterus to do with the pelvis, but anyhoo I can see if one of the BB osteo's can pop in and make sense of it... can see how it can effect baby's position in utero but not where the placenta goes....?
I agree - wonky pelvis can make your babies more likely to be posterior or in a funny position later on, but I can't see how it would affect where implantation occurs. Sounds very dubious to me?