The first app to get approved as birth control in Europe has now been green-lit in the US, despite controversy

Natural Cycles founders Dr Elina Berglund and Dr Raoul Schewitzl

Birth-control app Natural Cycles has been approved by the US Food and Drug Administration — the first app to be approved for contraception in North America.
The app uses an algorithm to tell women when they have the highest and lowest chances of getting pregnant, but it ultimately relies on men and women changing their behavior.
The app recently came under fire in Sweden when 37 women reported getting pregnant while using it.

A birth-control app called Natural Cycles has been approved by the US Food and Drug Administration, marking the first time an app has been approved for contraception in North America.

Designed by physicist couple Elina Berglund and Raoul Scherwitzl, the app doesn't involve a pill and contains no medication. It works by giving heterosexual couples recommendations about when to avoid sex or use protection, based on a woman's daily temperature measurements and the regularity of her period.

“Consumers are increasingly using digital health technologies to inform their everyday health decisions, and this new app can provide an effective method of contraception if it’s used carefully and correctly,” Terri Cornelison, assistant director for women's health at the FDA’s Center for Devices, said in a statement. “But women should know that no form of contraception works perfectly, so an unplanned pregnancy could still result from correct usage of this device.”

Natural Cycles only helps prevent pregnancy if people using it behave in the way it prescribes. The app also recently gained regulatory approval in Europe — the first app to do so there as well — but it came under fire in Sweden several months later when 37 women reported getting pregnant while using it.

Those pregnancies ignited a small controversy about how the app works and what it can — and can't — do. But Scherwitzl told Business Insider in January that he was not surprised women had become pregnant.

"We give red and green days and clear recommendations on which days to abstain and which days we consider the risk of pregnancy to be negligible," he said.

The problem with saying 'as effective as the pill using only math'

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Natural Cycles was initially portrayed by multiple news outlets — including Business Insider — as being "as effective as the pill using only math."

When is used properly, Natural Cycles may be comparable in effectiveness to the pill. But that doesn't always happen, as the controversy in Sweden revealed.

So the problem with these types of statements is that the app relies on couples to change their behavior and either not have sex or use protection based on the app's recommendations.

"Just like with the pill, you have scenarios where women take the pill everyday" and it's as reliable as possible, Scherwitzl said, and then there are "scenarios where they don't take it every day" and the reliability decreases.

How Natural Cycles compares with simply using a calendar

natural cycles app Natural Cycles' approach puts it in a larger category of birth control known as fertility awareness, which is similar to the calendar-based approach people have used for decades.

The company's founders published a study on the app's effectiveness in the European Journal of Contraception and Reproductive Health Care in 2016. The research involved 4,000 women between the ages of 18 and 45, and the results showed that out of every 100 women who used the app in a "typical" way for a year (meaning certain common slip-ups were accounted for), seven of them got pregnant.

That rate is and significantly lower than the traditional calendar method, which has an average fail rate of 24%, according to the CDC.

The "typical use" scenario for the pill leads to about nine out of 100 women getting pregnant within a year, so the study suggests Natural Cycles is on par with an oral contraceptive. But the app still leads to more pregnancies than would be seen among people using injectable birth control or an IUD. The typical use fail rate for an IUD is 0.2-0.8%, or less than one out of 100 women getting pregnant each year.

Apps can 'provide encouragement,' but still have key limitations

As far as the women who got pregnant while using the Natural Cycles app are concerned, the same European study found that more than half of them had unprotected sex with men on the days when the app advised against it. Those instances are evidence of a longstanding human reality: behavioral control is difficult, especially when it comes to sex, and not a guaranteed way to prevent pregnancy.

"While smartphone apps may provide encouragement, they can't stop [men and women] from ... sex altogether," Susan Walker, a professor of sexual health at Anglia Ruskin University, wrote in an article for The Conversation.

A handful of other factors can also get in the way of the app working correctly, including having multiple sex partners and having a partner who is not equally committed to birth control.

So if you're planning on using the app — or one of the dozens like it that have not been approved as medical devices — experts say you should have a predictable sex schedule, regular periods, be willing to check your temperature every day, and have the ability to abstain from sexual activity on consecutive days every month.

If you can do all that, the app could work for you.

"In the end, what we want to do is add a new method of contraception that women can choose from without side effects," Scherwitzl said. "I think there are many women who this will be great for."

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