Many of the "Messianic Prophecies" are a sad attempt of the Gospels authors to crow bar Jesus into the Old Testament.  Many are nothing more than misapplications of passages in the Hebrew Scriptures that were applied in hindsight in order to make Jesus "fulfill" Old Testament Prophecy.

For example: Isaiah 7:14 and Matt. 1:22-23.  The problem is that when we look at that passage in Isaiah, the original context does not look like a predictive prophecy about the Messiah, but an immediate Prophecy ("sign") given to Ahaz concerning his current national predicament.  Read the entire Chapter and you will see it clearly.  The Prophecy must have been fulfilled in Ahaz time in order for it to have any relevance or make any sense.  Besides all of this, in the original Hebrew, the word used here, almah, simply means "young woman."  It may be supposed that most young women were virgins, but in the original context, the miracle was not that Ahaz would see an actual virgin with a child, but that his enemies would be defeated by the time the child (maybe Isaiah’s child yet to be born) reached a certain age.