I don't think there is a job out there that doesn't change in some way when you're pregnant. In just the same way that nearly every job changes when you break your leg, have a headache or are insanely hung over from the night before. But I'm sticking to the pregnant one. And I'm also talking about my own job and line of work.
When I was pregnant with my older son, I was lucky (sort of!) in that I got to experience all of the morning sickness that I could handle in the comfort of my own home. I could be nauseous all day long. There were days that I threw up no less than three times before noon.
The second one was a bit more interesting to "hide", in that I had to wander to the bathroom to throw up, or be discreet about attempting to hurl in one of the conveniently located biohazard bags in the lab. There were more smells that tipped me off at work (yeah, beta mercaptoethanol is not a nice smell when you're pregnant...and neither is people being stinky in the bathroom on our floor!). I had more people help me through the morning sickness stuff, as in there were some who brought me ginger candies, one of the summer interns had access to some special ginger crackers designed for morning sickness. My own OB was also super nice (not that my other one with my 1st son wasn't nice...) in that he gave me a prescription for Zofran to take the edge off.
Working in the lab is also full of hazards sometimes, not just the smells, and I was a little more cautious about these sorts of things. I could have really done without a summer intern exploding cells in a microwave. There's virus work going on, and all sorts of other chemicals that have a chance to affect the unborn. But in the end, these are all just things to keep in mind, not to be paranoid about all of the time.
By the end of first trimester, things were still good. I was able to maneuver through tight spaces still (LOL!), my clothes still fit, and my appetite was returning. So far so good! Stay tuned for a second trimester version!