Desperate to have a baby, she turned to a close friend to be her surrogate. Then Lauren Litchtnauer discovered she was pregnant.

An Australian woman fell pregnant just weeks before her surrogate’s due date in a pregnancy that truly defied the odds.

Lauren Litchtnauer underwent 21 unsuccessful IVF treatments in her bid to fall pregnant to husband Myron.

The process saw the want-to-be mum suffer four miscarriages in a journey that consumed years of her life.

Desperate to help, friend Rosie Luik, a Brisbane-based model, stepped in to become the couple’s surrogate.

Source: Screenshot/Sixty Minutes.

The friends shared their emotional story on Sunday night's episode of Sixty Minutes.

"I think every woman out there who’s ever wanted a baby or had a baby would know exactly how it feels," Lichtnauer said.

Luik who already had three children of her own, grew desperate to intervene in her friend's ongoing fertility battle.

"I just blurted it out, I said, 'look, we'll discuss it later, but basically I'm going to have your baby'," Ms Luik said.

"I knew I was good at it. I'd had three babies. I had never had a complication. I just wanted to help Lauren."

Lauren Lichtnaeur and Rosie Luik. Source; Screenshot/Sixty Minutes.

The arrangement was further complicated when Lichtnauer discovered her own miraculous pregnancy.

"I started to cry and said [to Rosie], "I have something to tell you and please don't be mad and please don't hate me"," Ms Lichtnauer said.

"She said, "What?' and I said, "I'm pregnant", and she burst into tears."

"I was just over the moon," Ms Luik said.

An image of Luik's ultrasound. Source: Screenshot/Sixty Minutes.

Lichtnauer shared how the difficulties presented in her journey made her question whether she should even be a mother.

"I would question myself and berate myself over whether it was nature's way, or the higher powers telling me that I wasn't meant to be a mum," she said.

Luik said the twins she carried for Lichtnauer call her their 'tummy mummy'.

Altruistic surrogacy - where no money passes hands - is considered an acceptable and therefore legal process.

Paid surrogacy arrangements are illegal in Australia.

Mamamia staff share the unusual things you aren't told about giving birth:

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