It is not likely your 1-year-old child comprehends that your wife will be having a baby and all that entails. However, it is possible that your behaviors have changed in some way that your child has picked up on. Is your wife struggling with morning sickness? What kinds of aspects of it are you discussing in front of your child assuming she won't understand what you are saying? It is likely she has picked up on changes that she doesn't understand and it is completely possible it is stressing her out. Then again, she could be teething - those molars are somethin' else!
Just to be sure. I'd suggest talking to her about the pregnancy. Use some picture books like, "Arthur's New Baby" to help her preview what having a baby in the house will be like and what her role as big sister will be. Since she is so young, she won't understand it all and will need a lot of time to process the information so read your books and talk about it with her often and don't get frustrated when she asks the same question 100 times it is just part of her process. Get her a new doll with diapers and a stroller and a bottle etc. And role play how baby will be cared for down to diaper changing and burping. The earlier you start, the less the shock when the baby really comes.
Deal with her behaviors with understanding. She isn't even two yet so none of it is pre-meditated. Her behavior may or may not have anything to do with your wife's pregnancy so just do the normal, making sure she is getting enough rest, food, activity and loving attention etc. And this too shall pass.