Funny you should ask this. I got my engagement ring in 2000 and my wedding ring in 2001. We got pregnant with our first child at the end of 2002 and was unable to wear my rings from the early part of 2003 until 2 months ago...for the same reason that you are talking about. While I only had 10 pounds to get back to my pre-pregnancy weight from my first child, it never seemed to get back to normal in my hands. After a year or so, we had started planning for our second child (despite the lack of weight loss) and I felt foolish getting them sized only for them to change again. So, I literally didn't wear them for 4 years.
We had our last little blessing in February and by August, I had enough. I took my rings to the jeweler and had them size as is and I am very grateful for having done so. They are gorgeous and I feel great wearing them. And I would be happy to have them re-sized again IF I lose the weight but I am not going to wait for it to happen any longer.
As for the jeweler, they charged me about $250 to size the two rings 1 1/2 sizes.
Hope this helps. Good luck!