I don't understand why you would need a pendulum to keep on you during pregnancy. Wear an amulet, especially one that works against curses. Being pregnant you are very sensitive to negative thoughts and amulets that keep away the "evil eye" are generally the best route to take. You'll be amazed at how many dirty looks you can get when pregnant. Just about as many smiles.
For safe delivery, make sure all knots are untied in the room, the room is protected or you are wearing an amulet, and pray to or call to a spirit that is over childbirth/mothers/children--they are all different depending on your beliefs, from saints to guides/guardians to deities.