Devereaux tried to deny he knew he was HIV positive
A woman who found out she had HIV when she was pregnant with twins was infected by her boyfriend who had known he had the virus for nine years.
She was among four women unaware that Mark Devereaux, 41, had the virus when they had unprotected sex with him.
The 28-year-old woman chose to have an abortion after discovering she had contracted the virus.
Devereaux admitted four charges of culpable and reckless conduct. Sentence was deferred for reports.
The High Court in Edinburgh was told Devereaux was working offshore when his partner found a letter in their home in the north east of Scotland which said he was HIV positive.
When she confronted Devereaux he initially denied any knowledge of this - then claimed he had only known about his condition for a year.
It later emerged he had in fact known for nine years before he began their six-year relationship that he had the virus and could pass it on.
Devereaux, who now lives in Dundee, admitted that he had had unprotected sex with four different women without telling them about the risks involved.
Three of his victims escaped infection. The woman who was found to be positive got her test result when she was three months pregnant and decided to have an abortion.
The court also heard that another woman who had a relationship with the chef also contracted the virus but no charge could be brought because there was no evidence that Devereaux himself knew he was HIV positive at that time.
The charges he admitted in court covered a time-span from January 2003 to December 2008 and included various addresses in the north east of Scotland.
Devereaux was remanded in custody and is due to be sentenced next month.
Advocate depute Alex Prentice QC, prosecuting, said Devereaux was single, had no dependants and worked with an agency, travelling throughout the UK and abroad.
"This case related to the accused, in the knowledge that he was infected with the Human Immunodefiency Virus forming a number of sexual relationships and engaging in unprotected sex without disclosing to them that he was infected with the virus," said Mr Prentice.
He went on to describe how Devereaux was diagnosed in 1994 and, at that time, it was explained to him in detail that there was no cure, the virus would remain in his body and that he could be infectious.
Mr Prentice said in 2003 Devereaux got to know the 28-year-old woman who, after the truth emerged, took a number of months to come to terms with her illness and thought Devereaux had unwittingly passed on the virus.
"She had no idea the accused had been officially diagnosed in 1994. This only came to light a short time later," he said.
Devereaux later admitted to police that he had not told any of his partners about his HIV claiming he was "in denial".
He claimed that because he suffered no ill health himself he had been able to "completely forget" about his HIV diagnosis.
Mr Prentice said that was not true because hospital records showed he had received regular medication.
Lord Pentland called for background reports and added Devereaux to the sex offenders register.