U.S. women are overcharged $1 billion a year for the same health insurance coverage sold to men because they are women, a non-profit group calculated. The study by the National Women\'s Law Center in Washington analyzed the advertised premiums for men and women based on average current advertised premiums. Marcia D. Greenberger, co-president of the National Women\'s Law Center, said the study found that in states that have not banned gender rating, 92 percent of best-selling plans charge women more than men, even though the vast majority of these plans do not cover maternity services. In most states, it is common for a female non-smoker to be charged more than a male smoker simply because she is a woman. Nationally, 56 percent of best-selling plans charge a 40-year-old woman who does not smoke more than a 40-year-old man who does smoke. In states where maternity coverage is not mandated -- all but nine states -- 6 percent of health plans available to a 30-year-old woman provide such coverage, while in 25 states, there is no insurance plan available on the individual market that covers maternity services. Huge and arbitrary variations exist in each state and across the country in the difference in premiums charged to women and men -- even with maternity coverage excluded -- Greenberger said. The report found insurance companies -- despite being aware of the discriminatory practices -- have not voluntarily eliminated the inequities. However, Greenberger said in a statement, the overcharging will end with the Affordable Care Act, which prohibits gender discrimination. \"It\'s important that women learn how the law corrects insurance discrimination,\" Greenberger said.