Are you pregnant and do you want to have a healthy baby? You should avoid....

2nd - 8th week of pregnancy is for the fetus the most important! Because in this time is it the most sensitive for all harmful substances... such as:
VITAMIN A - in however small dose really harmful
According to previous information about vitamin A, I would advise you, don't take any vitamin preparation! Firstly consult it with your doctor!!!
alcohol - never use it!!! It can cause really serious damages to your baby!
drugs
no smoking
And one of the most important advices: DON'T DIET!!!! It's the most certain way how to make very serious damages to the fetus!!!!!
And every sickness makes problems during the pregnancy. So take care of yourselves!!! 

I will add more info to this topic later. These are the most important advices. I'll also add the consequences of usage these things during pregnancy. This topic is very wide.