Dr van Dam said she informed the teen of the risks of blood loss during labour. The teen responded: "I do not want blood."
She said the teen "seems to be of average intellect but is immature" and "believes naively that all will be well and that if anything happens she will be protected by her faith".
Associate Professor Campbell Paul, who is a child psychiatrist at The Royal Children's Hospital in Melbourne, told the court he discussed the matters with the teen at length.
She told him: "The Bible says it's wrong to eat or drink blood if you lose blood and have to let it go and pour it out on the floor."
Later, she also told him: "If the baby has to die, she has to die."
But Justice Cameron Macaulay ruled against the teen.
According to a summary of the judgment, seen by news.com.au, Justice Macaulay said the teen's level of maturity and understanding were contributing factors in his decision.
"I should consider whether she has sufficient understanding and intelligence to enable her to understand fully what is proposed and the consequences of her decision," he said.
"I should form a view about the extent to which her choice is a true reflection of who she really is, and what her beliefs really are, as opposed to the product of other forces.
"I am not convinced that overriding her expressed choice would so rob her of her essential self as to outweigh the loss she would suffer through losing her life or sustaining a catastrophic injury.
"In summary, I do not consider that allowing her, in effect, to choose to die or only survive with serious injury is in her best interests taking into account a holistic view of her welfare (physical, spiritual and otherwise)."
Justice Macaulay ruled that the hospital was authorised to administer blood or blood products "as considered reasonably necessary by two registered medical practitioners to save her life or to prevent serious injury during the course of induction of labour, labour, caesarean section and related procedures and the post-natal period in regard to her current pregnancy".
The hospital was forced to promise doctors would first use strategies other than the transfusion of blood to avert the teen's death or serious injury.
The girl's mother, who moved to Australia with her family as a refugee in 2009, told the court that receiving a blood transfusion would have a significant impact on her daughter's wellbeing.
"Being forced to have that done against her will would be something like having violence done to her or being raped," she said in a statement read to the court.
"She wants to do the right thing by Jehovah, by God."