I have been looking up a little bit about this drug because my Dr. wants to put me on it as well. here is a link that I found and it does list decreased fertility in both men and women.
http://ibdcrohns.about.com/cs/prescriptiondrugs/p/med6mp.htm , have you asked your Dr. about this? Good luck!!
Dx CD Oct '06 remarried July '05 mom of 3 boys ages 12, 15, and my baby born Oct. 07.