The typical price of a year's comprehensive insurance for a female motorist aged between 17 and 22 has increased by 4.7% to £1464, while the quote for a young man in the same age group has dropped by 1.9%, to £1858.
It comes despite the average cost of a year's comprehensive insurance being £789, its cheapest level for 12 months.
According to AA Insurance, young women drivers have been among the worst affected by a directive which came into force late last month, which bans insurers from taking someone's gender into account when calculating how much money they should pay.
Young women have traditionally been offered cheaper car insurance than men of a similar age as their accident rates have tended to be much lower.
Simon Douglas, director of AA Insurance, said he expected insurers to make further adjustments as they balanced out their businesses to take account of the new rules.
He said: "The gender directive doesn't mean that young male drivers are any less likely to suffer collisions.
"Young men represent just 8% of all drivers, yet still account for 23% of all those killed or seriously injured on Britain's roads," he added.