Mattel posted a loss of $73.2m (£51.1m) in the three months ended 31 March, more than the loss of $58.2m a year earlier.
Net sales fell 5.8 per cent to $869.4m during this period, down from $922.7m in the first quarter of 2015.
The company's shares fell around six per cent in extending trading.
"Our results in the quarter reflect very solid progress, particularly in light of significant headwinds we faced at the outset of 2016," Christopher Sinclair, chairman and chief executive of Mattel, said.
Earlier this year, Mattel unveiled three new body types for its Barbie doll brand. However, sales stills slumped three per cent in the first quarter, compared to a 14 per cent fall a year earlier.
Sales from its Other Girls brand — which includes Polly Pocket — dropped by 62 per cent during this period, while sales of American Girl fell 12 per cent.
But Fisher-Price reported a three per cent rise in third quarter sales, while Wheels — which includes Hot Wheels — enjoyed a two per cent increase.