How far back can they detect drugs using umbilical cord tissue?

Not where I look: If you end up under suspicion of drug use & I am asked to evaluate a newborn for such issues, I can usually find it. They do not test babies at birth under routine circumstances. However, if I need to explore the issue I can detect evidence of exposures as far back as the 2nd trimester. Either don't use or be up front with the docs so baby can be properly monitored for withdrawal.