Carols are much weirder than we think 

At last I found the answer in a book, Redeemer in the Womb, by the theologian John Saward, which brilliantly explores the unusual subject of what writers in the early Church thought about the months spent by Jesus in the Virgin Mary’s womb.

https://www.spectator.co.uk/article/carols-are-much-weirder-than-we-think/