When are you technically pregnant?

OK this is a purely TTC as Ellie stopped BF quite a few months ago.... but I have started to worry.

Last time I became PG I was incredibly niave and hadn't realised quite how many things you couldn't eat and drink and couldn't do until the doctor told me at the first visit to him, a few days after my period was late and I did a test (we were trying I just hadn't researched it that much).

Now this time I am aware that while PG you shouldn't eat things like Prawns, Pate, take loads of medicines, drink alcohol etc etc. Play hockey, go skiing and so on. However my question is this when are you really PG when it comes to these restrictions. As the earliest you know is once you are a day or 2 late. Can this cause problems... or at stages like when the egg is first fertilised do these things not cause any risks? It tooks us about 3months to get pregnant last time and who knows this time (I am now nearly 3yrs older), but I don't want to risk anything if you know what I mean.

Thanks all.

The first 3 months are the riskiest for these things, as this is when most of babies developement takes place (vital organs etc).
After 3 months, the baby is basically growing - so there is still a risk, but not so much as the 1st 3 months.

Saying this, at the start of my latest pregnancy, i got P'd at a wedding, went on a 3 hour motorbike ride, and took the morning after pill - and my little fella is just perfect!

When I 1st got pregnant I didn't know and went out and got drunk, not really drunk but more than tipsy, and that pregnancy didn't last. It probably was nothing to do with the alcohol, but next time (fingers crossed) I'll be careful from as sson as I think it might have happened. Its what an extra couple of weeks? You can get ultra early test's now that can give a posative 3 to 5 days after conception, I dont think a galss of wine, or piece of bree, my favorite, is more important than a possible bundle of joy. Just my humble opinion though.
http://cgi.ebay.co.uk/PRIVATE-10-ULTRA-EARLY-10-mIU-PREGNANCY-TEST-TESTS_W0QQitemZ310072805874QQcmdZViewItem?hash=item310072805874&_trkparms=72%3A12%7C39%3A1%7C66%3A2%7C65%3A12&_trksid=p3286.c0.m14.l1318