It isn't really expected to have more than one shower. It comes from a time where people were much more frugal and didn't need more and more. They took care of their items knowing they were going to have a family therefore it was not needed. They still had all the clothes from the first child and most of it was either green, yellow, or some sort of unisex outfit. They only need one stroller, one high chair, one car seat, etc...
However, all children are a wonderful blessing and should not do without.
I have hosted a second shower for a dear friend at church. She had 4 boys and was finally pregnant with a girl. Her hubby worked for Walmart and she was a stay at home mom. They were not poor but certainly not well off.
We had cute invitations, lots of food, cute games to play, lots of girly stuff, and I showed up, the co-hostess showed up, the pregnant mom showed up, and one person out of about 50 that were invited.
When I asked a couple of them why they didn't come they all told me they thought it was tacky and the parents should have prevented the pregnancy if the didn't have the means to take care of the child when it got there.
That is one of the reasons I don't go to that church any more.
Most of the time when a baby is born the friends who come visit will bring gifts to the hospital. If they visit during the first couple of weeks they will usually bring something too. That is what I would think is appropriate.