The Book of Isaiah was written by the Prophet Isaiah around 700 BC in which he prophesied the virgin birth of Jesus.
"Isaiah 7:14
Isaiah told King Ahaz, and the people of Judah, that God himself
would give them a sign or miracle. He then recorded it in Isaiah
7:14-16. Isaiah said an "almah," would become pregnant and give
birth to a son who would be called Immanuel. "Almah" refers to a
virgin, or an unmarried young woman who was expected to be a virgin
until after she was married. He also said that both the kings Ahaz
feared, would be gone before the baby boy was old enough to chose
between right and wrong.
I believe this prophecy had a dual fulfillment. The first fulfillment
was when Isaiah went into his "almah," or young wife, who was a
virgin until then, and she conceived and gave birth to a baby boy.
Isaiah 8:3-4. What was the miracle King Ahaz would see? Was it that an
"almah" young woman would conceive and give birth to a son? Certainly
not! Thousands of young women surely became pregnant and gave birth at
this time. A baby boy being born at this time would be no sign or
miracle to King Ahaz. What would be a sign or miracle to Ahaz was
that both the kings he feared, would be gone before the baby boy was
old enough to pick between right and wrong. This would show Ahaz
that the prophecy had come from God.
Isaiah 7:14 also predicted the birth of the Messiah. It prophecied
that a "almah" or virgin would conceive and give birth to a baby boy
who would be called Immanuel. The second and greater fulfillment
of this prophecy occured when Jesus was born. When Jesus was born an
"almah" in this case "virgin" conceived and gave birth to a son who
was called among other things "Immanuel." Mathew 1:18-25. For a
virgin to give birth is a miracle or sign. It is no miracle for a
young woman to conceive and give birth, but it is a miracle or sign
for a virgin to conceive and give birth. Jesus's virgin birth was
the sign or miracle God promised in Isaiah 7:14. In "Encyclopedia of
Bible Difficulties" Gleason Archer also argues that this prophecy
had a dual fulfillment involving a type of messiah as well as the
real messiah."
http://www.trustbible.com/jesus.htm