It is common practice now for children to be immunized for chicken pox. It is called Varicella vaccine, and since pediatricians have started regularly administering it, chicken pox has become increasingly rare in children. I recommend that both you and your boyfriend get immunized. It's common practice for adults to get the vaccine since it was not available when most adults were young, especially adults who work with the sick, elderly, or children. Your boyfriend should get it as soon as possible, you should get it after the children are born (when your doctor thinks it is safe for you), and the children should get it at one year with a booster 3 months to 4 years after the first. Your pediatrician will most likely automatically give this with the rest of your children's immunizations.Even though you have had chicken pox twice, you are still at risk for shingles. Shingles occurs when the original chicken pox virus goes dormant but stays in your system, and then resurfaces in adult years. Though infertility from infection can happen, it is very rare, so I would not worry about that too much. Congratulations on the twins!