Chrissy~ hopefully I'll have something more conclusive to tell you in a few days. I've heard the same thing and I've attached an article as to why it can work, but keep in mind it definitely is not foolproof and does not work for everyone. I am due for AF in about 2 days, but have had many symptoms identical to my last pg in the last few days. All HPT's have been neg, but my chart seems to indicate that if I did get pg, I implanted pretty late. So, I picked up a pack of OPK's yesterday. The first one I took was late evening and I thought was completely negative. I took one again this afternoon and immediately a light line popped up. I found yesterdays and compared them- the first one did eventually get a line as well, but there is a definite difference between the two. I have my fingers crossed. Granted, it may not work for everyone, but if it works for some, I'm going to try it. Just my opinion, though.
Melissa
http://www.thewisemother.com/OPK%27sasHPT%27s.html
http://www.FertilityFriend.com/home/29670