Does amitriptyline affect the birth control pill?

There are no known drug interactions between amitriptyline and the Birth Control pill
I did not find any contraindications to taking OBC pills with amitriptyline.

At the link there is a list of medications that before taking - your doctor should be aware of you taking amitriptyline.
Ive been on cerazette for a good few years and for about 6 months of that was also on amitriptyline and theres no affect at all. The doctor would have said if there was any affect. They are fine together.