I would agree with those people on here who are saying that it's only 9 months and that you have a very important role as 'life support' - why would you want to take any chances??!
My first baby was stillborn due to severe preeclampsia and HELLP syndrome. During that pregnancy I hadn't taken any chances at all with food/alcohol/second hand smoke, had eaten healthily (if rather a lot) but preeclampsia and HELLP have no known cause. I was told it begins at conception and is a process - nothing could have been done to prevent it.
Despite this, I knew I could be doing with losing some weight before trying again (comfort ate like mad after leaving hospital). I lost over 60lbs, then followed my "Eating well when you're expecting" book religiously. I again avoided everything that you should not have. I still had preeclampsia and HELLP, but this time 7 weeks later and DS was born at 31+3 but otherwise very healthy.
I know that had I been less careful (given my previous history and my spending months torturing myself about whether I could have been to blame somehow) I would have focused in on that and felt like I hadn't done all I could.
I will finish this post eventually, but just wanted to say that on behalf of those who have had their baby/babies die (myself included), it angers me that some people can take such a flippant view about your responsibilities towards the life you are carrying. While I was pg with DS1, my DP's mum would constantly tell me how it was all rubbish, that she had 5x double whiskeys every Friday night out during her pregnancy, smoked like a chimney etc etc. I was shocked at the time, but just feel anger towards her now. I know that what most of you are suggesting isn't quite the same, but you are still needlessly taking chances on something very precious.
Sorry to have gone on forever there...