My youngest son died in his sleep 9 years ago this July. In the child loss community, you're right in that "rainbow baby" means the subsequent child after loss (infant death, miscarriage, stillbirth, child loss in general). In all the support groups, a great deal of importance is placed upon the "rainbow baby". I never liked the idea, however. To each their own, and if it helps some women to think of it like that then I'd never pooh-pooh their manner of grieving, but I always felt like it put too much pressure on the "new" child. My subsequent child, a daughter, was awesome all on her own. I didn't like the idea of her "saving" us. It just felt like too much pressure on her, as well as on us. After all, we're meant to be completely fine now, right? We have our rainbow! 😏
Funny story, though...I absolutely refused to refer to her as my "rainbow." Nobody in my family did, either, because they respected my husband me. We had a name picked out from before we even got pregnant with her, and when I learned that she was a girl I was very excited. I didn't have a girl. We decided to name her after a popular Americana singer, kind of an older name that you don't hear much anymore. She was born, we named her, came home from the hospital...and then I looked her name up on the internet. Guess what it means? You guess it-"rainbow." Joke's on me.