Girls are falling out of love with Barbie. Global sales of the 54-year-old doll fell 12% in the three months to the end of June – the fourth consecutive quarter of declining sales.

Mattel, the world's biggest toymaker and the home of Barbie since she was invented by American businesswoman Ruth Handler in 1959, said girls were switching their allegiance to less clean-cut dolls, including its Monster High range of goth and ghoulish female characters.

But Mattel's chief executive, Bryan Stockton, said the company was still committed to Barbie, who "speaks to the aspirational roles that we know girls like to play out". He said Barbie sales, which still make the firm more than $1bn a year, will revive in the runup to Christmas, when it will launch a new range of dolls and accessories.

Analysts say Barbie's US sales have halved since 2000, mostly due to competition from Bratz dolls. Mattel lost a long intellectual property battle with Bratz's owner, MGA Entertainment, in 2011.

Mattel's total sales rose 1% to $1.17bn, below analysts' average estimate of $1.22bn. The company's shares dropped 7.1% to $43.03.