It is my understanding that Limbo was never the teaching of the Latin Church, but that the faithful could beleive it if they chose to. I also remember something about pe John Paul II bringing the topic of Limbo for a discussion.
When I was a kid, the nuns taught it, but it wasn't official dogma like the Trinity. Of course, as a kid, I didn't know the distinction between a theological opinion and a dogmatic declaration! No, I don't think it was ever an "official" teaching, although men such as St. Aquinas taught it in all but name by saying that such unbaptized children, who had no personal sin couldn't suffer the punishment of hell, but neither would they see the Beatific Vision.
Regards