Smartphone apps are the new hormone-free contraceptive (that even the NHS are recognising)

No more pills. No more condoms

If you think it's time to rethink your contraception method but you don't necessarily fancy trying anything as snazzy as the smart condom that can detect STIs and rank sexual performance (seriously, what!?), would you consider going back to basics?

Natural family planning (or fertility awareness or natural contraception) is on the rise in popularity because there are 0 side effects and also 0 disruption to sex.

But, where the 'pull and pray' withdrawal method is risky business, family planning apps like Natural Cycles and Daysy are now being taken a lot more seriously. In fact, they now count as contraception and could soon be available on the NHS alongside the pill and condoms.

So how does the algorithm of a contraceptive app work? It basically measures when you're fertile and when you're not by using your body temperature and recording your menstrual cycles.

If you follow the instructions (which we'll get into later), this method can be up to 99% effective as it learns your personal fertile window and will tell you to use protection during those days.

It takes around three to six months to sync with your cycle and your body temperature so you do need to use it for a while (alongside other contraceptives) for the first few months - and it's worth noting that this natural method will obviously not protect you from STIs.

Ovulation happens around the middle of your menstrual cycle (which counts as the day from your first period to your next period) and this is when pregnancy can happen. The apps count on users taking their basal temperature every morning to measure the small rise in body temperature when ovulation is taking place. But as sperm can live inside a woman's body for up to seven days after sex, you need to count the week before as a fertile window, too.

The two apps, Natural Cycles and Daysy, use the temperature method while free apps like Clue track your periods over a long duration and give you a rough estimate of your fertile window.

However, excessive drinking or lack of sleep can alter your temperature so it's best to not count those mornings! But, unlike other temperature-based systems, Daysy allows you to take your temperature whenever you wake up (rather than the same hour every day) and only needs you to have had three hours unbroken sleep to be able to measure accurately.

Natural Cycles was created by husband and wife duo Dr Raoul Scherwitzl and scientist Dr Elina Berglund (who worked on a Nobel Prize winning team back in 2013) to give women an alternative to hormonal contraceptives which have been linked to depression, weight gain, loss of libido etc.

Dr Elina Berglund tells us: 'Women around the world are interested in exploring effective non-hormonal, non-invasive forms of contraception - and now they have a new, clinically verified and regulatory approved option to choose from. Our high quality clinical studies, together with the required regulatory approvals, means we can provide women everywhere with a new option for contraception. Natural Cycles allow women to better understand their bodies so they can make choices that are right for them.'

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Natural Cycles is now used by over 150,000 women in 161 countries and is the first fertility tracking app for women to be regulated as a medical device.

Natural contraception

How do you go about using your cycle as a natural contraception?

'To get started with Natural Cycles a woman will need a basal thermometer to use in combination with the app. The user can start with Natural Cycles at any point in her cycle and she'll be asked a couple of questions about her cycle in the beginning.'

How does it work?

'A women measures her temperature every morning before she gets up and out of bed, enters it into the app and gets a red or a green day. A green day means she is 'not fertile' and can enjoy sex without protection (if she knows her partner well). On a red day she is likely to be fertile and needs to use protection in order to prevent a pregnancy effectively.'

How accurate is it?

'Clinical studies have shown that its effectiveness improves the use of Natural Family Planning to the level where it becomes comparable to the contraceptive pill. In numbers, this means that 7 women out of 100 become pregnant in a year (with the pill, it is 9 women out of 100). It is also worth mentioning that Natural Cycles is the only approved contraceptive app in Europe, which means that the clinical data has been carefully reviewed by authorities.'

Is it failsafe?

'No contraceptive is 100% failsafe. However, what makes Natural Cycles effective for contraception is that a unique algorithm analyses the temperature data on behalf of the woman. Traditionally, temperature data and other fertility indicators needed to be analysed directly by the woman, which can be difficult and prone to human errors.'

What is the actual biology behind timings?

'A woman can actually only become pregnant on 6 days in one cycle, this includes the lifetime of a woman's egg (24 hours) that is released at the time of ovulation and how long sperm can survive within the body (up to 5 days). Taking these factors into account and many others like a woman's cycle length, regularity, temperature and LH hormones it can be determined when those days are for her. Because every cycle and every woman is different, Natural Cycles does not assume that this will be the same for everyone. By taking all of that into account you usually end up with about 10 'red days' in one cycle where you need to abstain or use protection (condom) to prevent a pregnancy.'