work affecting my baby? help??

So I work as a waitress and I generally scared it's gonna affect the baby. I actually didn't notice how much manual handling I do. I'm avoiding it at all costs but my manager keeps constantly telling me to do things and I just keep saying they're too heavy. I don't know if I should tell him or not? I told one of the girls at work and she said she thinks I should wait to tell him, that she reckons the work we do won't harm the baby and she did it up until she was 8 and a half months! She also said one of the girls told them she was pregnant last year and they seriously cut her hours :/ what do you guys think? Are any of ye waitresses? Ps my doctor also said my work shouldn't affect the baby either :/ idk I worry all the time when I'm at work and I'm really conscious of it :/