LMAO it's so confusing isn't it. Noone seems to agree on the trimesters. I think we should just stick to you move when you get to 13 and 27 weeks since that's what everyone's been doing! To those who are confused by the week 12/12 weeks issue, think about it in terms of birthdays. When a baby is born, it is in it's first year of being alive. When it has its first birthday, it's reached the end of its first year and is one year old. So in the same way, when you get pregnant (well, two weeks before, but you know what I mean) you are in your first week of pregnancy, but you are not a week pregnant until the end of the week. HTH! It took me ages to get my head round it.