By recording your basal temperature with thermometer EBT-100 every morning, you can understand the cycle of your body and adjust your family planning accordingly. TAKING YOUR BASAL TEMPERATURE WITH ORAL METHOD ONLY Features: High Precision Thermometer with ± 0.05 ℃/ ± 0.09℉ accuracy. Test completion alarm: Thermometer will repeatedly soft "beep" sound 2 times after completion Product features a large blue backlit LCD.
Most women of a fertile age are probably aware that counting days in between periods as a family planning method is unreliable at best. The statistics show that as many as 24 out of 100 women who use this kind of birth control get pregnant within a year.
However, one fertility awareness-based method (that's what the healthcare world calls it) claims it can deliver better results than that. Swedish startup Natural Cycles has, according to its own data, taken about 4 percent share in its local contraception market with a solution that consists of an app and a simple oral thermometer. The startup was recently approved as a contraception method by a German testing organisation that certifies products for the UK's department of health. Natural Cycles is hoping to reach the British market this year.
Since it was founded back in 2013, Natural Cycles has raised $7.5 million (£6 million) in funding, with the bulk of that ($6 million) being raised last summer. Currently, most of its 135,000 users are in Sweden. The app, which is available for Android and iOS, has no free tier but a month-long trial, after which the user has to pay either £60 per year or £7 per month. In 2016, the company claimed to have recorded $2 million in revenue. It is yet to turn a profit.
Better than a calendar
Conceived by a family of particle physicists, Natural Cycles allows users to log their body temperature and applies relatively complex algorithms to determine the ovulation window based on that. The idea is that women can measure their body temperature after waking up every day (a free thermometer is provided with a year subscription), and then the app calculates how safe the day is in terms of fertility.
'Traditional fertility awareness methods are not very effective at all,' the startup's co-founder and CTO Elina Berglund Scherwitzl told Ars. 'This is mainly related to the fact that women used to have to analyse their body temperature on their own. This is extremely error prone, as not only do you have the possibility of human error at play, but you also have to use very simplified statistical methods, as well as only analysing one cycle at a time.
'Our algorithm takes all this away by doing more advanced calculations and simply returning either red or green, thus removing the human error. It is always extra cautious in the first months before it has enough data from this person to be able to safely give green days, without making any assumptions about the unique user’s cycle.'
On average, we're told, a woman that has just started using the app will get about 40 percent of “green” days a month. After the first three months of use, as the app becomes more confident, about 65 percent of days are shown as infertile days, said Berglund Scherwitzl. Citing commercial interests, she declined to go into more detail about the startup’s 'very long and complex' algorithm, which is said to be '60 full pages long.' It’s known that the parameters taken into account are 'temperature, menstruation, and optionally LH (Luteinizing Hormone) test information.'
The body temperature fluctuations at the time of ovulation and right afterwards normally range from 0.25°C to 0.45°C due to release of the hormone progesterone. It means that it can only be reliably measured by putting the thermometer under the tongue, as the skin might not be sensitive enough. Apparently, one of the tasks of the algorithm is to eliminate 'false positives,' i.e. the cases when the temperature changes due to other reasons, including sleep quality, alcohol consumption, illnesses, stress, etc.
Human error vs. contraception
The startup has held three clinical studies of its own and now claims that its Pearl Index of 7 is close to that of the pill. We're told that seven women out of 100 got pregnant over the year while using the Natural Cycles app to prevent it.
'This number does not only include the five out of 1,000 women that get pregnant due to intercourse on a green day, but also those who ignore the fact that they are fertile and decide to have unprotected intercourse on red days, or use less safe methods on red days such as withdrawal,' said Berglund Scherwitzl. 'As a point of comparison, the pill has a typical use Pearl Index of 9 out of 100. This mainly comes from women forgetting to take their pill.'
Since Natural Cycles is a fertility tracking service, it's sold as an app that can be used to prevent a pregnancy but also to plan it. About one third of the users are monitoring their fertility in order to conceive, we're told.
'This ratio has been stable, I think, because many of our users migrate across the two modes depending on their life situation,' said Berglund Scherwitzl. 'A typical user of ours is a woman between 25 and 30 that is in a stable relationship. She wants to have children in a few years and therefore stop using the contraceptive pill to stabilise her body first. Then she starts using Natural Cycles to prevent pregnancy until she is ready to plan her first pregnancy. Then she switches mode in the app and generally gets pregnant very fast as both the app and the user has gotten to know her body very well over time.'
It's worth noting, however, that there has been some criticism towards birth control smartphone apps. An NHS report, from April last year, warned that the Natural Cycles' clinical studies weren't rigorous enough. 'The retrospective design means data was not collected to specifically answer this question and may not be fit for purpose ... [and] most of the women in the study were aged 20 to 35, and therefore the findings may not apply to other age groups.'
Listing image by Natural Cycles
If your doctor has recommended you purchase a basal thermometer, you might be thinking, 'I already own a thermometer. Why do I need to spend money on a new one?' But that thermometer you've been putting under your tongue during flu season, or even in your tea to check its temperature before drinking it, can't do what a basal thermometer can. Regular thermometers check overall body temperature to identify or keep an eye on a fever. In other words, you use regular thermometers on sick bodies. Meanwhile, basal thermometers track the minuscule temperature changes that go on in a woman's healthy body throughout her menstrual cycle. Tracking these changes helps a woman find her fertile window. Basal thermometers can do this because as a woman's hormones change at crucial points in her cycle, her basal temperature rises.
You can use a regular thermometer anytime throughout the day, whereas you can only use a basal one first thing in the morning. Another important distinction between these two kinds of thermometers is that basal models are more accurate than regular ones. Basal thermometers can be accurate to a 0.1 degree Fahrenheit variance, while regular ones are often only accurate to a 0.2 degree variance. Detecting ovulation depends on picking up on the slightest of temperature changes, whereas monitoring a fever can mean tracking significant temperature fluctuations. A 0.1 degree fluctuation in a fever isn't cause for concern, but such a change in basal temperature can be significant for a woman trying to become pregnant.
Where exactly you place each of these thermometers is slightly different, too. You can use regular thermometers orally, anally, or under the arm pit. You use basal thermometers orally, anally, or vaginally. Interestingly enough, while you cannot use a regular thermometer to track ovulation, you can use a basal thermometer to track a fever, so long as it has a large enough range. If you only keep one type of thermometer in your home, you're better off having a basal one.