A 35-year-old Accrington man smashed a window at his girlfriend's house after going round to confront her about a love bite on her neck.
Hyndburn magistrates heard that Bryan Lee McNeill had "stewed" on the matter before going to confront his pregnant partner after he had been drinking heavily.
McNeill, of Stanley Street, pleaded guilty to criminal damage.
He was fined £100 and ordered to pay £50 compensation and £80 costs.
Philippa White, prosecuting, said mother of five Georgina O'Brien was eight weeks pregnant at the time of the incident. She was at home with two of her children and her sister when McNeill burst into her house.
"She could tell he was drunk and told him to leave," said Mrs White.
"He made some comment about her getting rid of the child and she shouted at him to get out.
"On his way out he put his fist through a window."
Gareth Price, defending, said McNeill had been pleased to learn of the pregnancy.
"His problem arose from a few nights earlier when his girlfriend had gone out and returned home with a love-bite on her neck," said Mr Price.
"Having stewed on that he accepts that he should not have gone round to discuss it when he had been drinking.
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