This is from an IVF article from my previous IF clinic, but the issue applies to anyone who's TTC. Check out the lines in bold:

"After the first 24 hours [after an embryo transfer], patients should continue to take it easy for additional three or four days. You can go back to work and lead your normal life, but strenuous exercise, chores and even sexual relations and intercourse should be avoided. Anything that causes uterine contractions could affect the implantation process."

So hold on. Having sex during the TWW could decrease the chances of implantation? Does this only apply with IVF, or can we generalize it for all types of implantation? (I can't imagine that the physiology is all that different at that point, but I could be wrong.) I thought I'd read about all of the factors that could affect your chances of becoming pregnant, but I guess not! Can anyone confirm this? Have you heard this from a doctor? Anyone see any exact statistics of how much this might affect implantation?