Intersex children are often operated on (PHILIPPE HUGUEN/AFP/Getty Images)

An Italian couple have been ordered to give their daughter a new name because a judge has said the one they picked is not “appropriate” for the child’s gender.

Vittoria and Luca, from Milan, named their child Blu, which is the Italian translation of word blue.

The couple chose the name because it stands for “bella luminosa unica” – meaning beautiful, vibrant and unique.

Under Italian law, however, children must be given names which are “appropriate” for their gender.

In 2000, a presidential decree ordered that “the name given to a child must correspond to their sex.”

Registry offices are to alert the courts of any names they think are unsuitable.

The couple told Italian newspaper Il Giorno their daughter’s name was entered on her birth certificate and she has gone by the name for the 18 months since her birth.

Despite this, they received a summons ordering them to appear in court to select another name.

The summons reads: “Given that this is a modern name based on the English word ‘blue,’ and that it cannot be considered unequivocally attributable to a person of the female sex, the birth certificate must be rectified by inserting another female name that the parents may propose during the course of the hearing.”

The parents are reportedly planning to challenge the summons by arguing that “Blu” is already used as a girl’s name in the country.

Luca told Il Giorno: “If we don’t come up with an alternative name, a judge will chose it for us.

“When we showed up at the registry office they warned us that there might be a risk of being recalled, but every year, according to ISTAT data, there are about seven Blus, mostly girls.

“We did not expect to have to change her name and a year and a half later, when our daughter now knows that she is called Blu and it is written everywhere.”

According to the Italian statistics office Istat, six girls were named Blu in Italy, the Local Italy reported.

He also told the newspaper Repubblica: “We cannot see why Blu is not accepted, it is an absurd discrimination.”

The parents added that the daughter of Beyonce and Jay-Z, Blue Ivy, also shares the name.

This is not the first time parents have clashed with the Italian authorities over names.

In 2012, a couple were forced to go to court for naming their daughter Andrea, which is traditionally a male name in Italy.