First preg I only found out after first trimester, didn't believe the blood results or my GP when he said 'yup 14-16 weeks' - to be fair, when I looked shocked at him he said "Well, I'm just an old poof, what do I know about these things??", but then I went for a scan and believed it.
Couple days later I'd recovered enough to phone my parents who did the usual 'how are you, any news?' and I said 'er, actually, I'm pregnant'
Mum's first question was 'are you sure' - yes, I have a photo and all, followed by 'whose is it?' - I told her it was most likely that bloke's who's been hanging around for 15 years and I got married to five years ago!
MIL's reaction was "for goodness sake - you're worse than bloody buses!" To be fair, she'd waited 20 years for a grandchild and then ended up with 5 in a year. :) Ds is the youngest.
This time MrNC let it out to his mum when I was about 6 weeks so I thought I'd better call my parents before she did. She said 'can I tell your dad you think you're pregnant?' and I said I'm definitely pregnant, just tell him not to get too excited quite yet as it's early days.
Since the 12-week scan my dad has had a totally dopey grin on his face as ds is now the perfect age for a grandson (3 - able to have a conversation and be impressed by everything Grandpa does - and not need nappies!), and so he's now over the moon about getting another, whereas he was rather bemused the first time round.