Rainbows as an omen of "a pregnancy that shouldn't happen" in ancient East Asian writing

Back when the 2016 trailer came out I was throwing out ideas with my brother on what the rainbow imagery could mean and how it ties in with the baby/pregnancy. So the earliest mention of rainbows in East Asian writing dating back to 10th century BCE in the 'Book of Odes', with rainbows always being used as an ill omen, such as a metaphor for an unwanted pregnancy, the arc of the rainbow being the swell of a womb with child.

Now we've got Kojima tweeting The Baby within a rainbow circle...

For a less "ancient mythology" take on the 'rainbow baby'... that's also a term used for a baby born after the mother had previously had a miscarriage or stillbirth.

Anyways it's fun to just speculate over the imagery of everything related to Death Stranding!