Would the doctor put me on medical leave when?

im a 21yr old working 12hr shifts at smith n wesson ( gun factor)! im 5 weeks and i lift pull carry and push for 12 hrs a day!! i kno that isnt good but im just askin, I DNT WANNA HARM MY BABY!! I KNOW ONW GIRL WHO WAS ON MEDICAL LEAVE FOR HER WHOLE PREGNANCY BECAUSE OF HER JOB!! SO IM JUS CURIOUS