What an adorable idea!
Make A Baby (Materials: Small containers of play-dough). Each person at the baby shower is given a small container of play-dough and everyone has 5 minutes to create a baby (using just one container). Then each dough baby is placed on a plate and presented to the mother-to-be who then looks at each dough baby and decides who's she likes the best. (You could always skip the judging part and also give the kids more time to make their 'baby'.)
This isn't so much a game but I think the kids' answers would be hilarious! You can give the kids pink and blue index cards or cut outs and ask them to tell you (or the other parents/teachers/volunteers) what their teacher needs to know about being a mom:
Baby Shower "Loving" Advice (Materials: red and white cardboard paper, scissors, and colored pens) - A great baby shower game to play is to have everyone write a "loving" message for the mother and father to be on cardboard cutout hearts in giving them advice for when the baby is born or during their last few days or months before the baby is born.
All of the quotes can be placed in a scrapbook with pictures from the shower for the teacher/mom to be.
This one could be fun with 4 year olds but I would just have them hold the straws in their hands, not in their mouths...and pass the pacifier from one to another. You could do some music and make it musical chairs like. Whoever is holding the pacifier on their straw when the music stops it 'out'.
The Pacifier Pass (Materials: Pacifiers with handles you can hold and straws) - Break up into teams of 4 or 5 people and have everyone stand in a line facing the person in front of them. The first person will place a straw in their mouth and place the straw through pacifier handle and in their mouth (the straw in their mouth not the pacifier). When you say "go" the first person passes the pacifier to the next person who should have their straw in their mouth and lets the pacifier slide down their straw (without any hands and no contact other than the straw). Everyone on the team passes the pacifier from straw to straw, no hands, no contact but lots of fun.
Dress The Baby (Materials: Baby life-size dolls, onsies, diapers, socks, shoes, shirt and pants for each baby doll and stopwatch) - Have each team race to see who can dress the baby doll the first. Each person (or team) must have everything correctly on the baby doll when saying finished. Points docked for missing articles or articles not placed on right.