Colorado health officials say teen pregnancies there have dropped 40 percent since the state began providing free intrauterine birth control devices to teenagers.

The experimental program, funded by a private grant and initiated in 2009, gave the free IUDs to teenagers and poor women.

Along with the drop in pregnancies, there was a 42 percent drop in abortions among teenagers as well, the Colorado Department of Public Health and Environment reported.

The drop in the teen birthrate was greater than seen in any other U.S. state, it said.

"Our Colorado Family Planning Initiative has helped thousands of young women who weren't ready to have children avoid pregnancy with affordable, safe and effective contraceptives," Colorado Gov. John Hickenlooper said in a statement last year when the initial results were tabulated.

In addition to IUDs, the program offered women the option of long-term contraceptive implants.

The greatest impact of the program was seen in the poorest areas of Colorado, where
unemployment is high and so are unplanned births, officials said.

At the start of the contraceptive program in 2009, half of the first births for women in those areas came before they were 21; by 2014, the same proportion of first births did not occur until the age of 24.

Unplanned parenthood for unwed women is a powerful driver of economic inequality, says Isabel Sawhill, an economist at the Brookings Institution.

"If we want to reduce poverty, one of the simplest, fastest and cheapest things we could do would be to make sure that as few people as possible become parents before they actually want to," she told The New York Times.

The program in Colorado, although undeniably successful, faces challenges as the funds from the private grant have begun to run out.

The Affordable Care Act mandates coverage of contraception, but many states are requiring payment even for coverage offered under the plan or limiting the kinds of contraceptives offered.

The Obama Administration is attempting to remove such limitations and restrictions.

In addition to lowering birth rates and abortions, the free contraceptive program proved to benefit Colorado economically, the state health department said; every dollar spent on IUDs and long-acting contraceptive implants translated to a $5.85 savings for the state's Medicaid program, which covers around three-quarters of teenage pregnancies and births.