(CBS11) – Natural Cycles is the first app approved by the European Union as a contraceptive.

The product is the brainchild of Elina Berglund and her husband Raoul Scherwitzl. The Swedish particle physicist was part of the Noble Prize winning team that discovered the Higgs boson. She told CBS11, via Skype, that the Natural Cycles discovery was personal.

“I was searching myself for a hormone-free contraceptive method, but I didn’t find any good products on the market,” said Berglund, the CTO.

The app relies on a woman’s temperature. Using a two decimal basal thermometer–more sensitive than a regular fever thermometer—a woman takes her temperature first thing in the morning. She enters it into the app, and an algorithm returns either a red or green day reading.

Green days mean the risk of pregnancy is low. A red day reading means there is a risk of pregnancy. On those days, women relying on the app for contraception should use another form of birth control or abstain from sex. It is why Berglund says the app is ideal for women in stable relationships.

“It is a compromise between a man and a woman in some sense. A man has to use condoms certain days and the woman has to measure her temperature every day. It is gender equal contraception,” said Berglund.

Berglund explains many of the women turning to the app, are doing so in search of a hormone-free alternative. Sara Flyckt, spoke to CBS11 via Skype from London. She had previously been using the birth-control pill and was looking for a more natural alternative.

“I try to live as organically as possible, everything from washing powder to my food. One day I started thinking ‘how come I have all these hormones inside my body when it comes to contraception?’ and it didn’t add up,” Flyckt explains.

Flyckt has been using the app since it became available. She relied on it for contraception, and then leaned on it when she was ready to add to her family.

“My daughter is a natural cycles baby,” she said.

Berglund says that’s typical of Natural Cycles users.

This technology may be new, but the basic premise behind Natural Cycles has been around for ages.

“Your grandmother knew about this. Your great-grandmother knew about this method,” explains Dr. Joe Chang. Chang is the Associate Chief Medical Officer for Ambulatory Services at Parkland. He is also a member of the Obstetrics and Gynecology faculty at University of Texas Southwestern Medical Center.

Your great-grandmother’s method has long had a reputation for being ineffective. Traditional family awareness based methods have a 24 percent failure rate according to the Centers for Disease Control. But Berglund insists, her unique algorithm which takes ovulation, sperm survival and other factors into account, makes all the difference.

“That’s a struggle for us as well. We do not want to be associated [sic] by the old version that wasn’t so effective. That’s also why we invest so much in our clinical studies to prove that this is really an effective form of contraception,” Berglund said.

In its largest clinical study, the company studied more than 22,785 women and 224,563 menstrual cycles and determined in typical use, the app was 93 percent effective. They say it’s comparable to typical use of the birth control pill.

“This app and success of the app depends on how you use it,” explains Dr. Chang.

“Understand that you’re trying to predict a future event based on a past event of your last ovulation. We all know that women’s cycles can vary. So there are some pros and cons there,” he said.

He says women with irregular cycles would not be good candidates for this method.

“You have to be healthy without other health problems that might affect your period, or your ability to become pregnant,” Dr. Chang said.

He says women should also consider whether they can can stick to the routine of taking their temperature daily.

Experts recommend speaking with your doctor to discuss the best method of contraception for you.

Natural Cycles is currently seeking FDA approval in the U.S. where it says it already has over 100,000 users.