The father already has equal shared parental responsibility (or "shared custody"). It is a presumption under the Family Law Act 1975 and gives both parties equal responsibility for the child unless an order by the court removes that responsibility from him. This is true even if he does not spend time with the child and means that yes, the father could pursue a relocation order if the child is moved a significant distance away from him without his agreement.
If the court were to hear your case, it would make orders deemed to be in the best interests of the child, and as such, you would need to show the court why the child's best interests will be better met by relocating with you. The child in utero will have fairly minimal impact on this because it will be the relationship with the father the court is concerned with first and foremost.
What you can do is organise a family dispute resolution conference with the father to try and negotiate an agreement about the child's care arrangements. You might wish to consider when the child will spend time with the father if you relocate, and how that time will be facilitated. If agreement can't be reached, then either party may be able to file an initiating application with the court for parenting orders.
Finally, at criminal law, parents can't be charged with kidnapping their own kids unless they remove them from Australia without agreement, in which case it's called abduction.