I was told at my NT scan that I had a low-lying placenta and not to worry about it at this point, but that it does cause spotting (I've had a small amount of spotting throughout). The tech said that some doctors will tell you not to exercise, lift things, or have sex, and some won't. Sure enough, we saw the OB today to discuss the results of the NT scan (first time we've seen her, we'd only seen the midwives in the practice until today) and she said to abstain from those things--though she added sex as an afterthought when I mentioned that I had spotted after sex a few times.

Does anyone have experience with this, or an experience of being told something different about what to do (or not to do) with a low-lying placenta? And can anyone explain to me what causes the spotting and why sex would be a bad idea? The internet--even Google Scholar--is coming up short!