DENVER (CBS4)– A new birth control study shows that longer-lasting options are much more reliable. An IUD or implant is 20 percent more effective at preventing pregnancy than birth control pills, the patch or ring.

The study published in the New England Journal of Medicine followed more than 7,500 women and found clear winners in terms of effective contraception.

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Medical student Kimberly Casten switched from birth control pills to an IUD, an intrauterine device, because of health concerns. She also enjoys the convenience.

“I don’t have to worry about getting my pills every three months. I really don’t have to think about it at all,” said Casten.

The study finds IUDs and hormonal implants are 20 times more effective at preventing pregnancies than short-term contraceptives like birth control pills, the patch or ring.

“You come into the office and we insert the IUD with a relatively simple procedure and then you go home and you don’t have to think about it for five or 10 years and you have excellent contraception,” said Rose Medical Center OB/GYN Dr. Suzanne Strubel-Lagan.

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About three million pregnancies in the U.S. are unplanned every year. Past studies have shown that about half of them are the result of contraception failure, often inconsistent or incorrect use.

“The method is only as good as the user and whether or not they’re going to be using it appropriately,” said Strubel-Lagan.

IUDs and implants have the lowest failure rate but they’re not very popular. Many women can’t afford the up-front costs, which can be more than $500.

The study showed that when IUDs were offered free of charge, 75 percent of women chose them.

Planned Parenthood of the Rocky Mountains would like to see better education about contraception.

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“What’s most important is for women to get the right birth control method that meets their personal needs,” said Planned Parenthood spokeswoman Monica McCafferty.