There is a new trend with non-traditional babyshowers being given in which men are invited to attend. However if you're deciding that you want to try out this new trend, you need to consider designing the baby shower so that men will feel comfortable attending.
Instead of sending out traditional babyshower invitations, create your own invitations using bright colors instead of pastel colors. Instead of using the term "Babyshower" rename the baby shower "Addition to the Family Celebration" or "New Birth Celebration."
Use both the names of the mother and father on the invitation. For example "John and Jane Doe invite you and your family to come join them in celebrating the expectation of their new baby girl or boy on **** (add date here)."
Find the perfect location. The Birthing Celebration should take place at a local park, or a community hall, or someone's home. Make the environment a festive party setting and refrain from using traditional babyshower decorations. Instead bring in a DJ for dancing, and have games that both men and women can play. Or if the location is at the park, consider games such as horseshoes, volleyball, or softball. Set up teams and then give out gifts to the winning teams.
Play a game. Games that you may consider playing should be designed so that men can also play. A fun game is the "Drinking baby bottle" game. Put beer into babybottles that have a tiny hole in the nipple and have the guys compete against each other to see who can drink the fastest. (You can also use non-alcoholic beverages).
Another traditional game that can be played is the "Purse game" but when men are in attendance you can call it the "Purse/wallet" game. Name off items that both men and women may carry in their purse or wallet. Give a gift to the man and the woman who have the most items. Sample items list for wallets: Credit card, chapstick, $50 dollar bill, discount card such as Sam's club or Costco, birth control (condom), money clip, picture of kids, wife, or girlfriend, business cards, video discount card like block buster, $100 dollar bill...(or anything else that a man might carry).