Telling my boss?? Lifting

Brittany
I just found im pregnant yesterday. I lift about 2 to 5 50lbs bags at work everyday. I don't think I'm ready to tell my boss, but if I don't tell her I won't have an excuse to not lift the bags. I've being doing this job for almost 3 years. Is it ok to lift these bags or should I just bite the bullet and tell my boss?