Vaginal yeast infections are caused by a disturbance to the bacterial balance inside the vagina.

Antibiotic medicine is NOT the treatment for yeast infections. Antifungals or topical creams are. As a matter of fact, antibiotics can be the cause of a yeast infection.

You should work with your doctor to determine the reason why it is occurring every month as it can be a sign of something more serious like diabetes.

It can also be that you need to change something like the type of soap you use, the type of panties you wear, the type of menstrual protection you use, other medicines you use or habits you have.

It is not impossible to get pregnant when you have a yeast infection but it does make it more unlikely as the environment in your vagina is not its normal sperm friendly environment. You can also pass it on to your partner.

I think that the previous response, although thorough was a little frightening and unrealistic.
Any doctor will tell you that a yeast infection does not prevent your chances of getting pregnant and in actuality once you become pregnant you are more prone to contracting a yeast infections because your body goes through hormonal changes. Increased sugar content in vaginal secretions will allow your yeast to feed on the sugar and grow, causing an imbalance of too much yeast and therefore an infection.
So if you're trying to get pregnant try to clear the infection before conception, but you have nothing to worry about.
Once pregnant if you do get persistent or reoccurring infections I would ask your doctor about "THRUSH" which is the only issue I have come across where the yeast infection can possibly pass to your baby's mouth during delivery, but again this is completely curable and not a huge concern.
So be calm and don't let anyone use scare tactics to intimidate you and cause anxiety about issues that are not of any serious concern. Good Luck!!