Board Thread:Naruto Discussions/@comment-25192437-20150307225810/@comment-1458758-20150311002209

Elveonora wrote: Except Gaara had those rings already right after he came from her vagina. Did she put the seal on him while he was inside of her vagina? Okay, just to get this out of the way, babies aren't grown in the vagina, they're grown in the womb, the vagina is visited fairly briefly on the way out, but that's about the sum of the relationship between babies and the geography of their mother's nether region.

As for whether or not she put a seal on him before he came out, the manga is explicitly clear that they sealed Shukaku inside of Gaara before birth, so if they can get a bijuu into the kid before he's born, I don't see why the idea of enactng some form of jutsu or seal on him before his birth is out of the question.