My absolute best advice is to be forthright. For the safety of the baby and the mom's legal protection. I know it is worrisome if you've been using when pregnant that they may take the baby or something like that. Just know they test the babies once born and can detect anything in their system. If you are an addict, this is an opportunity to be honest and perhaps resources will be offered for help. If not, still. Resources and education can help. Being high as a parent of a newborn does not work. So, I would tell your doctor. I really would. There is NO zero nada judgement but that they want what is best for you and the baby.
I'm here to talk to if you need it.
That's likely going to depend on the facility and their policies, along with any local laws. The consent form should outline what testing will be done. This forum has members from all over the world, so it's not possible to determine what may or may not be required at a specific facility in a specific state or country.