I gave up all caffeine before trying to conceive. Since I cannot prove a negative, I can't say whether it helped or not but I did get pregnant the first month we were trying.

BTW, you can have caffeine during pregnancy. Go read Expecting Better. She totally debunks the "recommendations"

Anonymous wrote:Actually studies show that caffeine cause the Fallopian tubes to spasm. So if you really can't give it up, at least stop immediately prior to Ovulation and the week after.

http://www.sciencedaily.com/releases/2011/05/110523121142.htm

http://www.sciencedaily.com/releases/2011/07/110720142359.htm

OP here-- thanks everyone! I think I will give it up during ovulation and two week wait, and then have some nice coffees as a treat during my period. The one time I previously got pregnant happened to be a cycle in which I had given up caffeine, so maybe it makes a difference for me.