Yes...tell your doctor immediately!!! If you don't, your baby's health is at risk and he/she will be taken from you at birth!!!
You have to inform your obgyn.
Under medical care, everything will turn out all right.
With-holding the information endangers your baby.
If you have not come clean with your obgyn and let them help you they will call cps . SO PLZ TELL YOUR DOCTOR ASAP . how far are you along and how much are you taking .I know telling your doctor is very scary but they will help you