I've been with the company 2.5 years, and its always been said that when X leaves, i'll take over in his role, we've always spoken openly about this.
Boss has just turned to me and said next Thurs he wants to do mini-appraisal, to discuss and make sure we're both on the same page in regards to new role which i'd start in about 2 years time. 
I'm currently 10+4 with my scan a week on Tuesday, and although I know I don't have to disclose that i'm pg (and I wouldn't consider before telling folks etc), I do feel a little guilty about it all.
Our industry in seasonal, so boss is saying i'd need to start learning now as X only has 2 harvests left before he goes.
But I secretly know (or hope after scan in a week and a half) that I'll be having a year off from September, therefore vito'ing one of those two 'training' years.
Do you think this will cause a prob when in 3/4 weeks I do tell him i'm pg???