Mine would always be really sore for a week before AF. So much so, that getting them was a relief. The month I fell pregnant they acted exactly the same...but ended up staying that way for about 10 weeks or more because of the BFP!! Very sore, I couldnt lay on them. Also I went from a 12C to a 14D in bras! I joke with DP that I will probably be a DD by the time my milk comes in.