The singer, 35, is already mum to daughter Ruby, 14, and son Dexter, 12, and last year welcomed daughter Freda.
Speaking on Rob Beckett and Josh Widdecombe’s Parenting Hell podcast, she said since having her first two children she had become a bit of a “tree hugger” and so created a "birth palace" outdoors to welcome her third child.
However, Mother Nature intervened and Church ended up having Freda inside on the bathroom floor.
She said: “I did love birth, but then my third birth absolutely came and b**** slapped me in the face.
"I was so unbelievably overconfident, because the first two times, I was 21 and 22, and my body knew just what to do. I had two home births, they were quite simple. Don't get me wrong it was still birth. It's still incredibly intense and all the rest of it.
“But it was like, the third time around. I have become quite a nature lover stroke tree hugger, like quite deep hippy in the interim of having my first two and little baby Freda.
"And so I set this birth palace outside basically amongst the trees. I dried flowers, I mean, it was so involved. It looked like a Baz Luhrmann set, candles everywhere."
The singer said she laboured under the trees overnight and that it was "beautiful" but then it started to rain so she decamped inside and ended up having Freda "screaming" on the bathroom floor.
She said: "It started drizzling at about 7am, and I live next to a golf course. And I could really hear the golfers.
"My noise... I am a noisy woman anyway but if I'm in any sort of pain... My noise started to up I thought, 'This is not going to work'."
Church had Ruby and Dexter with her former partner Gavin Henson, and shares Freda with her husband Johnny Powell.
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