Yes, wedding showers are allowed... I just don't see why - since they are - baby showers wouldn't be. At least they have some sort of reason for birthdays, although I think personally Witnesses recognize and internally celebrate their b-days. I know a Witness who, despite being compliant with the faith, got really excited on each birthday and watched the clock for the "exact time" she was born. No cake, but certainly recognition.
anyway...
SLM