I had one - but in 'what to expect when you're expecting' they say they are 'VERY rare'. There aren't necessarily any 'signs' (i had no idea - but then, i wasn't even aware you could miscarry without bleeding) but i think as long as you continue to have pregnancy symptoms you can be reassured by that. that said, though, pregnancy symptoms - nausea, sore breasts etc - can disappear now and then and one shouldn't read too much into it.

Having had a missed m/c I've found it hard not to worry about having another this time round. I think if you're going to miscarry the kind where you have bleeding and cramping is more common, so if you're feeling fine, try not to worry too much - or ask your practitioner about it so they can check everything's OK and reassure you.