I find a Baby Shower Invitation more touching than a Bridal Shower Invitation.
Believing that this is a celebration of life, a welcoming of another gift from above makes it more important than a union of two adults. Probably because babies are so precious, so new to the world that giving them something as special as this makes me want to share it with every parent in my own circle. Actually, anything concerning babies are pretty special. Them being so small, so dependent of us gives more meaning to every event that happens to them.
If I can, I would give free baby items or free baby samples to every parent in the whole wide world to show them how special they are to have a kid of their own. Being a mom myself does this to me. Sometimes even teary eyed to just see a kid hug her mom, or a dad taking care of a wee bit. At times just seeing baby pictures makes me truly sentimental. Wedding gifts are nothing compared to having a baby because babies are the best gift there is!
Thus, baby showers are one of the best occasions I am ever invited to.