I would give it a little while before you decide to resize.
Sorry if this is a personal/rude question..did you put on extra weight other than baby during pregnancy? If so, this may take a little time to come off.
I also had a friend who had swelling in her joints during pregnancy, so this could also be it and may take a little time to settle down.
I was able to put my rings back on comfortably around the 2mth mark.
Our bodies do funny things during pregnancy, it sometimes just takes time to get back to where we want to it to be if it get's there at all