The actress plays Maxine Minniver in the Channel 4 soap, who went into labour after being driven off the road by villainous husband Patrick Blake (Jeremy Sheffield), who then delivered the baby!
She told What's on TV: "The whole birthing thing was a lot of fun to do because I've never given birth... so it was something a bit different and fun and it wasn't in a clean hospital, it was in a dirty shack."
Nikki added: "[I had no] coaching. I spoke to a lot of people who've had children and the main point was you're in a lot of pain so that's what I've tried to do, to be in a lot of pain...
"Jeremy was wonderful. He did think my face was very funny, but to give him credit I do look hilarious, so I don't mind people laughing at me a bit."
Co-star Danny Mac interjected: "I really wanted him to say, 'Don't worry I've been in Holby! I've played a doctor, you'll be fine!'"
Jeremy starred in Holby City for three years in the early 2000s.
Watch the interview about the Hollyoaks train crash and birth with Nikki Sanderson and Danny Mac, above.
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