i had a vit d definciency before i was pg and was advised when i got pg that bubs could have issues with bone density and rickets. my doc said to take calcium and vit d together as well. i havent really taken much of the vit d supplements but thats mainly cause of hyperemesis (sp?) and all supplements, even ones to calm the tummy like ginger and slippery elm wont stay down (slight tangent there). i tend to try and sit in the sun everyday for a while, even if it is even just in the window when its freezing outside, not sure how useful that is but no one has mentioned bubs having supplements after birth to me either.