On one visit, she brought an empty medical syringe concealed in her clothing, intended for self-insemination with material he had prepared for her.
Austin-Saddington, from Weymouth, received a suspended sentence after pleading guilty to charges of misconduct in public office.
The court considered her serious health condition — she is now wheelchair-bound after a fall — when deciding on the sentence.
Trengrove, from Camborne, Cornwall, had been serving a 13-year extended sentence for serious offenses prior to this incident. He was handed an additional two years and three months for his role in the inappropriate relationship.
Bournemouth Crown Court heard that Austin-Saddington began working at HMP The Verne in July 2019. In 2020, she received a written warning due to concerns.