When/how to tell infertile coworker?

My office mate has been very open about her and her husband's struggle to get pregnant (trying for 2+ yrs). She talks about it almost daily. I am 10wks and want advice on when and how to tell her. I've known her for less than a yr.

She has said the past that she hates it when people tiptoe around her but I don't know how to best share my happy news when she is struggling...

Any advice?