Does a pregnant mother have to be addicted to drugs for a baby to be born addicted?

i have a friend who occasionally used oxycontain throughout pregnancy about once every 2 weeks in a small dose no more then 20 mls at a time and stoped for about a month and a half in the middle of the pregnancy. she is now 37 weeks and has not done anything in a week and does not plan to for the remainder of her pregnancy. Will the baby be born addicted? She has never experienced withdrawal symptoms from the oxys. Pleasee someone answer.