Proposed health care premiums for 2017 in nine states are expected to rise by an average of 12 percent over 2016, reaching an average of $503 a month. This is according to a health care researcher’s analysis of insurance company rate filings.

The average increases are projections for an average silver plan covering a 50-year-old nonsmoking man.

“As in years past, proposed premium increases vary dramatically by state and by region within states,” said Elizabeth Carpenter, senior vice president at the health care consulting firm Avalere Health.

“In most states, premiums for the lowest costs plans appear to be rising less than for the silver metal level as a whole,” she said.

Premium hikes are likely to cause many consumers to switch health plans. UnitedHealth Group’s announcement that it plans to withdraw from many markets around the country next year will mean policyholders will no longer be covered and will have to shop around for other coverage.

“Consumers may have to switch plans in order to avoid dramatic rate increases, but competitive options should still be available in most regions in the U.S.,” Caroline Pearson, senior vice president of Avalere, said in a news release.

Here is a rundown of proposed average monthly silver plan premiums for 2017 compared with final premiums for 2016 in nine states.

District of Columbia: $434, up 9 percent

Indiana: $493, up 6 percent

Maryland: $474, up 15 percent

Maine: $583, up 18 percent

New York: $525, up 15 percent

Oregon: $517, up 17 percent

Virginia: $538, up 19 percent

Vermont: $513, up 8 percent

Washington: $449, up 5 percent

The average monthly premium for the nine states profiled by Avalere Health was $503, for an average premium hike of 12 percent.

Many Insurers File for Double-Digit Increases

Health insurers in many states are seeking double-digit premium increases for 2017 in the individual and small group markets. This development sets the stage for heated political battles in state legislatures over the future of “affordable” health care reform.

Health insurers file their rate increase requests with regulators in the spring before undertaking public hearings. After negotiations with regulators, rates are finalized later in the summer.

In Delaware, to take just one example, Highmark Blue Cross Blue Shield is asking for a 32.5 percent increase in the individual market, while Aetna Inc. is asking for a 25 percent hike and Aetna Life a 23.9 percent hike, Insurance Commissioner Karen Weldin Stewart said .

In Delaware’s small group market, Highmark is asking for a 2.7 percent increase, while Aetna Inc. is looking for a 23.2 percent increase and Aetna Life for an 18.6 percent increase.

Stewart said the requested increases are occurring in many states across the country. She reminded consumers that proposed increases are not final rates.

Many insurers have filed for double-digit increases in Connecticut and Texas.

In the nation’s most populous state, California, premiums under the health care law may rise as much as 8 percent on average, state experts predicted earlier this year.

Among the major factors dictating premium changes for 2017 are the underlying growth in health care costs and prescription drugs, the rate of health care usage, and the elimination of reinsurance funds to help with the Affordable Care Act transition, according to the Society of Actuaries.

Premiums also are affected by changes to the risk pool, a fee levied on health insurers, the small group market staying at 50 employers or fewer in most states and changes in health provider networks, the said.