A Polish baby came into the world under the influence of alcohol because his mother was drunk during labour, police said Friday.

Tests 12 hours after the boy's birth revealed a level of 1.2 grammes of alcohol per 1,000 grammes of blood - the equivalent of a bottle of wine or two litres of beer for an adult drinker.

In comparison, blood-alcohol limit for drivers in Poland is 0.2 grammes.

The baby was in intensive care on Friday, and although he was in a stable condition, doctors said they feared his brain could have suffered lasting damage.

His 34-year-old mother fled the hospital in the southern city of Zabrze after the birth on Tuesday but was arrested the following day, when tests revealed no traces of alcohol in her blood.

"The woman is already the mother of five children. Their grandparents have custody because she has (already) been deprived of her parental rights," said police spokesperson Marek Wypych.