CHICAGO (Reuters) - Studies released by a reproductive rights research group on Thursday show that unintended pregnancies cost U.S. taxpayers about $11 billion a year.

Two studies by the New York-based Guttmacher Institute looked at the public costs of unintended pregnancies. A third study looked at unintended pregnancy rates at the state level.

The research found that in 2006, 64 percent of births resulting from unintended pregnancies were publicly funded, compared with 48 percent of all births and 35 percent of births resulting from intended pregnancies.

The research comes as some states consider legislation that would limit funding for non-abortion family planning services, said Elizabeth Nash, a Guttmacher public policy associate.

"We're absolutely concerned that either the restrictions on family planning funds and cuts to family planning funds will have substantial impact to women having access to these services," Nash said.

"Women may end up with unintended pregnancies or not use the birth control that's best for them."

Indiana, for example, has a new law that would cut funding to Planned Parenthood of Indiana, Nash said. Planned Parenthood has sued, claiming the law could cost the state about $4 million in Medicaid family planning funds.

Other states considering limiting family planning funding include Kansas, Texas, North Carolina and Minnesota, Nash said.

A publicly funded birth on average costs $11,647, according to the research. The two studies varied in their methodological approach, but both came up with a figure of over $11 billion a year for the taxpayer cost of unintended pregnancies.

In Louisiana and Mississippi, more than 80 percent of unintended births are publicly funded, Guttmacher found. The percentage was over 70 percent in some other states, including Texas, the District of Columbia, North and South Carolina and Kentucky.

The study that looked at unintended pregnancy rates by state found the numbers were highest in the South and Southwest, including Mississippi and Florida, and in states with large urban populations, such as New York and California.

(Editing by Jerry Norton)