The only confusion is in the use of the term “immaculate conception” and how it applies. “Immaculate conception” does not mean virgin birth, but rather, refers to a post hoc cleansing of Mary’s status so that she did not posses original sin. This clensing was applied at the moment the sperm of her father wiggled into the ovum of her mother, according to the Ineffabilis Deus of December 8th, 1854.

The Virgin Birth, on the other hand, is the birth of Jesus despite Mary’s not having had any sex with Joseph or any other human man. Or at least having not conceived Jesus as a result of such sex. The word “birth” in this term is a metaphor or codeword for “conception.” In this case, Jesus was “incarnate” and specifically, incarnate of Mary herself (which is why she needed to be immaculate) and the Holy Spirit.

The process appears to have been facilitaed by angels.

It is all described in various religious texts, but the best way to find out how this stuff works is here.

and

The ASA said in its ruling: “We considered the use of a nun pregnant through immaculate conception was likely to be seen as a distortion and mockery of the beliefs of Roman Catholics.

I contend the ASA mocks the beliefs of Roman Catholics by presuming to declare what is likely to be seen as a distortion and mockery of the beliefs of Roman Catholics by not even understanding what immaculate conception is.

A woman, nun or not, does not become pregnant through immaculate conception. It’s conception by normal, every day means. The only difference is that Original Sin is not passed on. Or is it removed? Either way, it ain’t there in foetus.

And I’m fairly certain that the ASA (with the complainants) thinks the bub in the nun is the Christ. Nope. It’s the mother of the Christ. A common misunderstanding, but if you’re going to take it upon yourself to protect the sensibilities of religious folk, then understand their damn theology!