Is it safe to scuba dive in shallow water 20-30 ft when you are trying or have just become pregnant?

DEFINATELY NOT!!!! The largest pressure change is between 30 feet and the surface, You could give the Baby decompression sickness without showing symptoms yourself !!!

You shouldn't scuba dive during pregnancy, the safety issue really hasn't been ruled out, but I wouldn't risk it. On the health waiver form, it asks if you are currently pregnant or trying to become pregnant, if maked with a "yes". They will not allow you to dive. I'm guessing it's not a good idea. If you are a regular diver it probably won't do any harm but it is not something to do for the first time.