A Welsh woman obsessed with a man who only slept with her once has been jailed after convincing the man that he had fathered her child.

Charmaine Wilson, 25, was jailed for four months on two charges of making a false document after she forged a birth certificate to make Liam Griffiths, 31, believe he was the father of her baby, which was actually a friend's, Wales Online reports.

Wilson met Mr Griffiths three years ago when he gave her a lift home after a night out.

Prosecutor Helen Edwards said after a one night stand Wilson terminated her pregnancy but became obsessed with the young man and started bombarding him with messages via text and social media.

Wilson, who worked at Bridgends's Princess of Wales hospital, later met Mr Griffiths' family at the hospital where they were visiting the victim's grandfather who was being treated for cancer.

The health worker then introduced a baby to Mr Griffiths' mother, Cathryn Thomas, as her grandchild to the family's complete shock.

To complete the ruse Wilson later forged a birth certificate for the child and the results of a DNA test after Mr Griffiths provided a sample.

The baby that Wilson claimed was hers and Mr Griffiths was a friend's who the health worker had looked after as unpaid carer.

"The grandmother bought the boy clothing and toys and on his second birthday a big party was held." Ms Edwards told the court.

"The family decided to build a log cabin in the garden of the family home where Mr Griffiths and his son could live."

Wilson's lies began to unravel in May when Mr Griffiths posted a picture of the boy and the under-construction cabin on Facebook.

When a friend of the couple saw it they asked Mr Griffith what he was doing with their cousin.

"The mother then confirmed it was her son," Ms Edwards said.

In a victim's impact statement Mr Griffiths said everything reminds him of the child he lost.

"I tried to keep Charmaine on-side and changed my lifestyle for access of the child I thought was my son," he said.

"The only word I can use to describe Charmaine and what she has done is mental. I cannot believe she would deceive me in this way. I am devastated and heartbroken to have lost a child I thought was my son."

Ms Thomas told the court she felt like she had lost a child " that I honestly thought was my grandson, who I had bonded with, fallen in love with and spoilt rotten".

"Finding out the truth of the matter, and that the baby had another name, and that Charmaine had simply borrowed him in passing off as her own has caused me nothing but upset and grief," she said.

"I haven't stopped crying for days. I'm still trying to be strong for my son, who has been awful since he found out the child he thought was his own, having had a DNA result, was not."

Wilson's lawyer Stephen Jones said it was the case of a lie that "snowballed out of control".

He said the deception was sparked by Wilson aborting her child, leaving her feeling "heartbroken" and as if she had lost everything.

He said she had shown "huge remorse for the pain she had caused".

A family member of the child, who did not want to be identified, said the boy's real mother had been through a tough time and had a newborn so Wilson was helping to raise the child.

"She had no idea Wilson was doing this, when she found out she was sickened," the relative said.