I have known women who ski during second trimester, though they are admittedly good skiers. My daughter is in Crosssfit with a woman who continued workouts until the last week. It's what your muscles are trained for that counts. The fetus is well protected. Which said, lifting weights requires proper posture and lifting with the legs, not the back. When your bump gets in the way of doing it right, sometime in the third trimester (?), you should ask for help when necessary. Your co-workers will be happy to pitch in. Just my opinion.
I totally agree with ppowb. You should be fine. Lifting should not cause any issues to the pregnancy and certainly not birth defects. If you are farther along and begin to have false labor or Braxton hicks contractions (not labor contractions, feels like tightening of the abdomen) then talk to your doctor but this will be unlikely. By the way, how heavy are the things you are lifting? I guess that you should mention that weight to your doctor to make sure.
Hi. I wanted to check in with you. How is it going? How are you feeling? How is the job? And last, lol, is your 20 week sex reveal ultrasound coming up? It seems like it should be. That is a magical appointment!