WASHINGTON (AP) -- The stork apparently has trouble landing in northern New England. New Hampshire has the lowest, Vermont the second-lowest and Maine the eighth-lowest birth rates in the country.

A new U.S. Census Bureau report says that in 2006, New Hampshire's birthrate was 42 babies per 1,000 women of childbearing age. The national rate was 54.9 births per thousand.

Vermont had the second-lowest rate, at 42.2. Counting Washington, D.C., Rhode Island was third-lowest, at 45; Massachusetts had the seventh-lowest rate, at 46.1; and Maine the eighth-lowest, at 47.3.

In Vermont, officials say the low rate could accelerate a demographic shift that threatens to shrink the state's work force.

"Everybody has interpreted the shrinking population of working-age people as a mass exodus by young people out of Vermont, but that's really a very small part of the story," University of Vermont economist Art Woolf told The Times Argus. "The biggest part of the story is that people just aren't being born."

Secretary of the Agency of Commerce and Community Development Secretary Kevin Dorn said the shortage of working-age Vermonters is a major economic hurdle facing the state. In the last year Vermont's work force fell by about 2,000.

"This low birthrate is a component of a much bigger problem," Dorn said.

The median age of Vermont's work force is 42.3, the highest in the nation. And the Vermont Department of Labor estimates the work force will shrink over the next two decades as wage-earners reach retirement age.

Gov. James Douglas said efforts to bolster the work force by luring young professionals back to the state is crucial to economic development.

"Employers cite adequacy of the work force as one major concern for future success here," Douglas told the newspaper. "We have employers who have created good jobs and want to create more, but they need a qualified work force to take those jobs."

Experts attribute Vermont's low birthrate to its racial homogeneity and high education levels among women.

Recognizing a similar potential workforce problem in New Hampshire, the state university system and business leaders are working together to try to encourage college graduates to stay in the state. They'd like to increase the retention rate from 50 percent to 55 percent. Thus the group's name: The 55 Percent Initiative.

A survey found that in-state and out-of-state students say New Hampshire has high quality of life, is a good place to raise a family, has available housing and is close to natural resources. But 40 percent of graduates say they believe there are few or no jobs in their field in New Hampshire.

The program is working with students at the University of New Hampshire, Plymouth State University and Keene State College to develop a marketing campaign aimed at retaining seniors and recent graduates.