Don't want to give too many details here as prefer not to be identified in RL.
But, she is in the second trimester and is complaining that she can not take a one to two hour flight to go to the project site. This is a normal part of her job. She says she can't do it. Other people in the office are getting fed up with all of her special requests.
And if she can legally refuse to do her job, can her employer require a sick note from the GP? Can she be replaced (i.e. her project given to another employee while she does something else from her usual desk keeping in mind something else might not be as rewarding as the job she does now)? Is is important that person responsible for this project appear on site from time to time, and she has all but refused to go.