Here is a great article snipit that should help you understand what vitamins could be of benefit when trying to get pregnant:
"One of the potential ways that vitamins can help aid in conception is in the area of cervical mucus. Cervical mucus is a jelly-like substance that a womanâs body produces during her monthly cycle. Cervical mucus is an important part of conception. Cervical mucus helps sperm to survive once it is inside of the womanâs body, and it helps sperm to get transported to the egg so that it can fertilized the egg and get pregnant fast.
Vitamin C is one of the vitamins that can aid in conception. Vitamin C is thought to increase the amount of water that is in your cervical mucus, and can help cervical mucus to become more plentiful. In addition, vitamin C may be able to aid in conception by making the walls of blood vessels stronger, and fighting infections, which can interfere with fertility."
Also there are further articles speaking to the benefit of Vitamin C and Vitamin E - as well as Folic Acid as mentioned above.