Hello,
Welcome to Just Answer and thanks for your question. Marijuana metabolites can be detected for six weeks in chronic users (which is what the baby would be since marijuana crosses the placenta).
Yes, the marijuana use would not show up by 36-38 weeks.
Nurse Practitioner
Board Certified Nurse Practitioner, MS, RN. Private practice and hospitalist experience.
I hope the remainder of your pregnancy is healthy and the little one will be fine. It will not be THC+ if you stop smoking now.