Why Baby Showers Are Not A Good Idea
In a shower there's so much less control over the temperature of the water that it's very possible to burn a baby's sensitive skin. With a bath, you can monitor the temperature of the water the baby is getting into and know exactly how warm it is. Also if you have a shower with a very high pressure nozzle this can do damage to the baby's eyes and even teeth.
The bottom line is, if you're thinking about doing these "baby showers" you shouldn't. Bathe your child in a sink to start off so that the water can't get too high and then gradually transition to a bathtub and never leave the water running to go off and do something because you might forget and find the baby face down in a full tub. It can happen to the best of us, but it is avoidable.