what do you tell a person...?

How do you help a person out when all the facts point to the opposite? I have a friend that wants a baby really bad... She has done everything that you can think of to try and get one... She has been on the fertilty drugs, seen a specailist, had her partner tested... she has been through every test possible, but still no baby... The docotor has not said that she can't have children it's just hard for her to concieve... Now from me looking in, it seems like she just can't have them.. She does not understand why she is being denied this road? what can I do or say to help her... She is my best friend and we both have cried over this, been depressed over this, and have prayed for this.... All of our friends are having babies and she can;t even be happy for them because she is so depressed about her not being able to have a kid... what do I do...