Mutual of Omaha said it did not comment on pending legal matters. John Hancock did not respond to a request for comment.

Women typically account for about two-thirds of the long-term-care insurance claims paid annually, said Jesse Slome, spokesman for the American Association for Long-Term Care Insurance, an industry group. Last year, companies paid $7.5 billion in claims.

The effect is that women will now pay several hundred dollars more a year in long-term-care premiums than a man would for a comparable policy, according to the association’s 2014 report, based on data from insurers. (The new gender-based premiums apply to new policies, not policies that were in place before the change took effect.)

If you are a single 55-year-old man in good health buying a new policy, you can expect to pay $925 a year, on average, for a policy providing $164,000 in current benefits, without any built-in inflation protection. If you are a woman of the same age and health, though, you will pay an average of $1,225 a year for the same policy — a difference of $300, or more than 30 percent.

The difference in premiums is greater if you buy a policy that builds in inflation protection of 3 percent, compounded annually, for your benefits. (Your pool of benefits under this option would grow to $325,000 at age 80.) The same 55-year-old healthy man would pay $1,765 a year for that policy, but a woman would pay $2,307.

A typical single woman will pay an average of 12 percent more than in 2013, the association found.

The impact of gender pricing for couples who buy a policy together varies by insurer, Mr. Slome said. Some companies price policies for a couple based on their rates for single men or women, while others offer a blended couples rate. (Genworth said its gender-specific pricing applied only to single policies.) Insurers typically offer a significant couples discount. The average premium for couples for insurance with inflation protection has risen by about 3 percent from last year, the association said.

Here are some other questions to consider about long-term care insurance:

■ How can I get the lowest premium available?

Mr. Slome urges consumers to shop around because premiums for similar coverage can vary significantly among insurers. Rose Clayton, an insurance broker in Orange County, Calif., advises women to keep the extra premium in perspective. When female clients learn of the higher cost for women, she said, they’re not pleased, “but it’s not a deal-breaker.” For many, it reinforces the need to plan for their old age. “One only has to visit a nursing home or assisted living” facility to see the impact of women’s longevity, she said.