I'm 21 weeks. I saw my obstetrician today for a follow-up from my 20 week scan, and he said my placenta is low-lying. He said if it was assessed over four grades, with four the most serious, then I'm a 1. It has nearly 20 weeks to move, so I'm really not too worried.
But then he mentioned that it looked "a bit unstable" and that I can't do any more running (ha ha!), jogging, yoga, pilates, cooking or cleaning. Think he might just have thrown the last two in to soften the blow. Sex is safe for now apparently. 
My last baby arrived six weeks early and we never really found out why, so I'm a lot more worried about this than about the position of the placenta and kicking myself that I didn't ask him more questions. I asked what this meant and he said just a greater risk of bleeds. He didn't say anything about a premature delivery, but I'm not sure whether that was just not to worry me, or whether it's because the possibility is actually very remote.
Has anyone else had this? I've googled it, and found lots of info about an "unstable lie" but virtually nothing about an "unstable placenta". I think I will call him back - he won't be in clinic again until tomorrow - but would also like to hear from others how they are managing it. How easy do I have to take it in practice?