Mr Rees-Mogg is probably the most honourable and honest politician you will find and I hope this country is lucky enough to have him as Prime Minister one day. He has said he will always support the majority democratic vote and, at the moment, that is that abortion is legal up to a certain number of weeks. However, if given a free vote in parliament as was in the case of gay marriage, he will vote according to his conscience.
The reason he was asked this question was probably because the left, liberal media is terrified of him being in a leadership position because they don't like politicians who are that honest and principled and he is also a leading Brexiteer so they are trying to get in early and ruin his chances of being the Tory leader after Mrs May. This is how a certain sector of the media works. I wonder if they will interview all the Muslim, Jewish or Hindu Members of Parliament and ask them the same question.
Personally, I have never understood why - if a baby is killed 4 months after it's born it's called murder but if a fetus is terminated 4 months before birth it is called legalised abortion. The end result is the same, the end of a life. Perhaps the fetus should be asked if it's pro choice before it's discarded because it happens to be inconvenient for whatever reason. .