M.L.
I think baby showers for 2nd and 3rd children are way more accepted than they used to be. Especially if there is a gender difference. I didn't get one for my daughter (2nd girl, 2 years apart) but I was disappointed. Not because of the gifts, but because I believe every baby deserves to be celebrated! However, if you want to stick to the "rules", the guideline is, baby showers are acceptable if the 2nd (or 3rd) baby shower is attended by people who did not attend the first shower. But I say, go for it!