Announcing to parents

Hi everyone--

I have opportunity in a few weeks to announce to both my parents and my in laws at the same time that we are expecting. I will be exactly 7 weeks, which I know is on the early side but these are our parents so if something did go wrong I would be telling them anyway.

Anyway! Any tips or ideas on how to tell them? I might just blurt it out like an idiot (cheap and effective) but I'd love to hear how other people have shared the news with parents/in laws.

Btw this will be the first grand baby for BOTH sets of parents so it is extra exciting!