Becky
Let's consider the passage in context:
[10] Again the LORD spoke to Ahaz,
[11] "Ask a sign of the LORD your God; let it be deep as Sheol or high as heaven."
[12] But Ahaz said, "I will not ask, and I will not put the LORD to the test."
[13] And he said, "Hear then, O house of David! Is it too little for you to weary men, that you weary my God also?
[14] Therefore the Lord himself will give you a sign. Behold, a young woman shall conceive and bear a son, and shall call his name Imman'u-el.
[15] He shall eat curds and honey when he knows how to refuse the evil and choose the good.
[16] For before the child knows how to refuse the evil and choose the good, the land before whose two kings you are in dread will be deserted.
[17] The LORD will bring upon you and upon your people and upon your father's house such days as have not come since the day that E'phraim departed from Judah -- the king of Assyria." (Isaiah 7:10-17)
The timeframe on this is around 700 B.C.E. It describes an alliance between Syria and the northern kingdom of Israel, whose combined forces threaten to destroy the kingdom of Judah. Isaiah assures Ahaz, King of Judah, that God will protect his kingdom. He prophesies that a child will be born to a certain woman, and that, before the child learns to distinguish good from evil, the two kingdoms threatening Judah will be destroyed (verses 15 - 16). The prophecy contained in Isaiah 7 clearly addresses this particular political crisis; it in no way refers to the concept of a Messiah. Furthermore, Jesus was not born until 700 years later; his birth could hardly offer any reassurance to King Ahaz.