Besides gender, other factors include age, geography and medical conditions, he said.
"What is done is done on an actuarially confirmed basis," he said. "A lot of it's maternity-driven, there's no question about it."
Once people reach their 50s, it typically costs more to insure men, he said.
The NWLC found that in West Virginia, individual health coverage for 55-year-olds costs between 1 and 16 percent less for women than for men the same age.
Codispoti said maternity costs can't explain all the differences in pricing. NWLC also studied maternity coverage in the individual market, finding that nearly 60 percent of policies it studied didn't offer it.
This summer, NWLC analyst Brigette Courtot shared the center's West Virginia findings with state lawmakers.
Researchers had studied the state's best-selling health plans in Charleston, Huntington, Parkersburg and Wheeling. They found:
Five states have banned individual-market insurance companies from using gender as a factor for setting rates: California, Minnesota, Montana, New Hampshire and North Dakota.
Six have prohibited the practice for group insurance: New York, Maine, Massachusetts, New Jersey, Oregon and Washington.
Earley said it would be "redundant" for West Virginia to pass legislation next year, because national lawmakers have already taken up the issue in the current health-care debate.
America's Health Insurance Plans, which represents 1,300 insurance companies, supports provisions in national reform legislation that would end gender rating.
The U.S. House health bill would prohibit gender rating for both individual and group insurance plans. The Senate version would prohibit gender rating for individual plans and for groups up to 100.
But those reforms wouldn't take effect for several more years, Codispoti said.
"We're certainly encouraging states, 'Don't wait,'" she said. "Women are hurting now. It's discrimination, period, and women shouldn't have to wait to end that discrimination."
Staff writer Kate Long contributed to this report. Reach Alison Knezevich at alis...@wvgazette.com or 304-348-1240.