i dont think that is true. Any employer has to carry out a risk assessment on pregnant employees to see if there are any risk associated with your job to the unborn child, so they would have done it anyway
I had a look at the website you have quoted and to be honest someone writing in a book that "some researchers speculate that noise may be hazardous to a foetus" is hardly scientific or researched proof that working on an airport causes unborn babies to go deaf, so your doctor has really shot herself/himself in the foot by using what 1 person thinks to even add to an arguement! if i was the occupational health nurse or doctor doing the risk assessment i would be wetting myself at "evidence" such as this and it seems unprofessional of your doctor to use it.