A man punched his girlfriend with such force to the nose that she fell, hit her head on a wall, and began bleeding and having a fit.
Swansea Crown Court heard how Lee Bird had got into a heated argument with his girlfriend Kirsty Williams on September 1 last year after the pair had been out drinking, joined by Miss Williams' sister Sarah.
The row gradually intensified throughout the evening and both accused each other of speaking to people of the opposite sex. There was talk of the two women carrying on to a party, to which 31-year-old Bird responded: "So you can talk to all the boys."
The pair continued to argue and raise their voices and Bird then pushed his girlfriend backwards onto a bed using both hands, the court was told.
Miss Williams then slapped Bird to the left side of his face then clenched her fist and punched him to his face. At that point Bird lost his temper and punched Miss Williams to the nose causing her to fall down, hitting her head on a hallway wall.
Prosecutor Dyfed Thomas explained how she lost consciousness temporarily and began bleeding profusely from her head while she also began having a fit.
Emergency services arrived at the scene at 11.45pm where they found Miss Williams lying on the floor. The account from paramedics, Mr Thomas said, was that she appeared to be having a fit but may have just been upset.
Bird was arrested on suspicion of assault at which point he said: "Yeah, it's fine. She hit me and I hit her back. I regret that."
Miss Williams fractured the bridge of her nose, an injury which extended to both cheek bones.
A wound to the back of her head measured two to three centimetres long and required five staples to close it.
Bird, of Elphin Road in Townhill, Swansea, pleaded guilty to grievous bodily harm.
Mitigating, James Hartson said: "He is an enhanced prisoner at HMP Parc and has a job as a barber.
"His is in contact with the injured party and she visits him regularly. That speaks for itself regarding the status of their relationship.
"The defendant, by his guilty plea, expresses remorse for his conduct. He was being attacked by her before he struck her.
"He accepts the force used, even if justified, was not reasonable in the circumstances."
Sentencing Bird, Judge Keith Thomas said: "You're a young man of substantial build and punched her to the nose with a substantial blow, causing her to fall down and hit her head. It was clearly a very forceful blow."
Bird was jailed for 16 months.