Is it safe to use fertilizer while pregnant?

Depends. It depends on the fertilizer and how you handle it. Some fertilizers can be dangerous to the fetus. See http://www.Ncbi.Nlm.Nih.Gov/pubmed/8056207.
No. Fertilizers contain many toxic chemicals harmful to an unborn child, which can be transmitted thru the air or on the skin.
Yes with caution. You can use fertilizer during pregnancy but you need to be very careful with it. You should wear gloves (surgical, not gardening) to prevent a lot of exposure. If you get fertilizer on you while working with it promptly wash it off.