I strongly urge you not to rely on anecdotes as that would be asking for trouble. You may be fine but if they do ask for a specific form at check-in and you don't have one, you may not be flying.

There is a public page on BA website that specifically deals with medical conditions etc:
http://www.britishairways.com/en-gb/...-and-pregnancy

In addition you need to make sure that your daughter is genuinely fit to fly for her own sake (and yours) by clearing it with the specialist. Don't just ask for advice from an average GP as they might not quite understand the effects of flying on her particular situation.