Amitriptyline

I am currently taking Amitriptyline 25mg everynight for headaches.... i know this is a very low dose so it does not worry me (becoming adicted/effecting moods etc) my worry is me and my b/f are thinking about trying for a baby. i was reading the information about amitriptyline and it says..

"If you are pregnant or trying to concieve, do not take". i have not consulted my doctor on this yet and thought i would ask on here if anyone knows why not and does it apply to an extreamly low dose. (175mg minimun is used for anti-depressent)......

i was wondering if anyone had any light on this?????