Basically Vitamin A comes in two forms - Retinol from animal origin and Beta-carotene from plant origin.

Retinol is a known teratogen which means that it causes birth defects in a fetus. Anything containing Vitamin A (Retinol) should be avoided during pregnancy.

Beta-carotene is not harmful at all to the fetus and should be that form in all woman's/pregnancy vitamins. If you look in the ingredients table it should specify which form the Vitamin A is in.

Doubletrouble, the main difference between normal vitamins and preg ones would be the extra folate.