If you are feeling paranoid, take a towel and put it behind the back seats where it can be retrieved if her waters break. You don't want that stuff getting all over your aeroplane!
Would be best to keep her out of a control seat so that there will be no issue with full and free movement of controls or related harm in the event of an emergency.
If there is any anxiety, encourage looking out to the horizon and breathing normally with slow deep breaths rather than rapid short, shallow breathing.
It sounds like a short flight so I don't think you will have any dramas. Make sure the weather is nice...!
