You can assume a lot of things
The point is, why bother? You will never know for sure because this man isn't being honest with you. My experience with alcoholics has been that they will get high by any means possible. My ex-A had as big of a problem with dope as he did with booze. My mother switched from booze to tranquilzers. What he is using doesn't matter. The more you focus on him and what he's doing, the less you focus on you and your baby. I hope you put your time and attention on the positive things in your life.
Peace,
Gabe