Businessman demands his girlfriend sign a prenup three days after giving birth.

The agreement a wealthy businessman asked his girlfriend to sign three days after she gave birth to their child has been torn up by the Family Court.

The Australian reported the ‘prenup‘ only offered the woman $25,000 in shares if the relationship broke down.

It was reported the Sydney man was initially horrified to learn of the pregnancy, as he had allegedly told his girlfriend he never wanted to be a father.

The businessman allegedly told the Family Court he initially wouldn’t allow the woman to move into his house as he wanted to protect his assets.

The woman was later allowed to move in on the provision she signed the agreement.

The identity of the woman has been protected but she was referred to as Ms Zagar in court documents.

Zagar was said to have refused to sign the agreement while she was pregnant on the advice of lawyers.

It was reported the woman only had $3000 to her name and owed $5000 in credit card debt when she eventually signed.

The woman told the court she had told the father of her child she needed to secure funds for her future.

"You have assets and I will be left with nothing. How can I sign a document like that? I need to provide for my future," she said.

The businessman was said to have responded by giving Zagar a choice of either signing or leaving the home.

The Australian reported the man had given the mum employment during their time together but terminated it after they split.

It was reported she was also sent a letter of demand to vacate the house.

The man told the court he needed "security" for the assets he had fostered. “I have built up my business and own my own home. As it has been a rocky relationship thus far, I need security for my assets including my superannuation and investments," he said.

The presiding authority Justice Robert McClelland found the recent nature of her birth had deeply impaired her ability to make a sound decision.

"She signed the agreement despite the clear advice of her lawyers not to do so,’’ he said.

A legal battle over assets and child support is expected to follow.

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