Actually, no. You're confusing immaculate conception and virgin birth. Immaculate conception is the Roman Catholic dogma that the Virgin Mary was conceived without original sin:
http://www.newadvent.org/cathen/07674d.htm In the Constitution Ineffabilis Deus of 8 December, 1854, Pius IX pronounced and defined that the Blessed Virgin Mary 'in the first instance of her conception, by a singular privilege and grace granted by God, in view of the merits of Jesus Christ, the Saviour of the human race, was preserved exempt from all stain of original sin.'