It is unconstitutional--and unethical--for physicians to participate in evidence-gathering against pregnant women suspected of being addicted to illegal substances without informing them of their constitutional rights or gaining their informed consent.
Argument that physicians called upon for expert testimony in court have an ethical duty to educate the jury by offering opinions based upon published, clinically based evidence and peer-reviewed medical literature.
When a pregnant woman is knowingly causing harm to her unborn child, there are various legal interventions that can be taken to protect the rights if the fetus.