How can we explain the dreams which somehow show up in reality?

Actaully this happened to me last November. I was browsing facebook and came across one of my sisters friends I hadnt seen in a long time. I dont actually know her all that well, but I knew who she was when I saw her. Within a weeks time I had a dream about her that she just had a baby boy and I was at the hospital holding her new little boy. That was it...very strange because as I said I dont really know her all that well. With in a week of the dream...I saw her post something on on of our mutual friends pages so I thought I would share my dream with her...LOL...I think she wanted to kill me...lol...she said no more for her...she had a seven year old and she was done...not to metion it hadnt happened in the last 7 years so she didnt even know if it was possible. Again...a week or so later she sent me a message telling me she was pregnant...I thought she was joking...I didnt believe her at all...I thought she was playing a trick on me. As time went on...we found out she was going to have a boy...and just a few months ago...lil Owen arrived. That was the first and only time that has ever happened to me.