You mean "virgin birth" not immaculate conception:
Definitions of "immaculate conception" on the Web:
* The teaching that Mary was conceived without original sin. Typically believed as true in Roman Catholicism.
www.gbgm-umc.org/quakerroad/daleapolo/Dictionary4v1.html
* Roman Catholic holy day first celebrated in 1854
* (Christianity) the Roman Catholic dogma that God preserved the Virgin Mary from any stain of original sin from the moment she was conceived
wordnet.princeton.edu/perl/webwn
* The Immaculate Conception is a Roman Catholic doctrine which asserts that Mary, the mother of Jesus, was preserved by God from the stain of original sin at the time of her own conception. Specifically the doctrine says she was not afflicted by the privation of sanctifying grace which afflicts mankind, but was instead filled with grace by God, and furthermore lived a life completely free from sin. ...
en.wikipedia.org/wiki/Immaculate_Conception