I asked my Vet when my Taffy was prego and he told me that the body reacts by slowing the calcium production if is supplemented from outside, in high quantities, and recomended the plain yogurt a couple of times a week and then increase it after the pups were born.. so that is what I do .. other people might do different and might do things a lot different, this is just what works for me.
hugs,
CArmen in nj