Hi Belfie, I had gastro a couple of times during my second pregnancy (had never had it in my life prior to that time!). I didn't get it as badly as you obviously have, but short answer (for me) was no ... it didn't affect bub one iota. I saw my GP not long after my second bout, and she wasn't worried about bub either as I too was feeling movement etc after having had the gastro bug.

Not sure about how you can avoid it. Like having a cold or something, it can strike when you least expect it. I'd imagine probiotics would help more in your recovery than actually helping you avoid it though. I'm no medico, but maybe your best defence is to keep up good hygiene habits - wash hands after supermarket trips etc, plus try and steer clear of anyone who's got it. Not so easy with a toddler though ....

Good luck - hope you feel better soon.