I cannot think of anything that should be concerning for a pregnant "fist time" fish owner. I have had fish most of my life (currently have a large koi pond) and frequently get in there and clean gunk out, even while pregnant. I actually spent quite a bit of time standing in my pond during my pregnancy with DS, trying to cool down.
Are you planning on getting a regular fish tank with a pump and filter, and not a bowl? If so, you should be able to do 10% water changes once a month, and that will be almost all the cleaning necessary. The only other thing needed will be periodically wiping algae off the inside glass of the tank, and changing the filter cartridge (or rinsing it off) when it gets full.
Cristina, Mama to Michael 03-16-06, Nathan 01-16-11, and an angel 01-20-09,
Go with your gut, follow your heart.