5 Facts About Ovulation


Whether you’re planning a pregnancy or tracking your fertility, understanding when you ovulate is key. This week we’ve gathered a couple of cool facts around ovulation that maybe you weren’t aware of. Find out below!

 1. The female egg cell is the biggest cell!

Most cells in our bodies cannot be seen without a microscope, but the female egg cell is big enough to be visible to the naked eye. Pretty cool!

eggcell2. Women are born with all the eggs that she will ever produce during her lifetime.

We are born with 1-2 million immature eggs (follicles) in our ovaries. Once a woman reaches puberty roughly 500 of these will mature into an egg cell that can be fertilized throughout our lifetime.  

3. The egg cell only lives 12-24 hours

Once released, an egg can only be fertilized over the next 12-24 hours. Sperm, on the other hand, can live up to 5 days if the sperm encounters the right environment.

4. Normally only 1 egg is released each ovulation.

However, some women have the potential to release two eggs during one cycle, one per ovary, which is how fraternal twins are made! This is only possible within a 24 hour period. Afterwards, ovulation is prevented by the high progesterone values in your body, which is what Natural Cycles detects in your temperature (rise of 0.2-0.45 °C).

naturalcycles_ovary5. You can get your period although no ovulation has occurred.

We see in our Cyclers’ data that around 5% of the cycles are in fact anovulatory – meaning that no ovulation has occurred. This is completely normal and nothing to worry about. The bleeding that follows is then due to the estrogen rising, rather than the progesterone decreasing, and is thus not exactly the same as a normal menstruation.

This was all for now Cyclers!
Please comment if you have any questions and read more in our support portal ask.naturalcycles.com.

What your cycle says about your fertility

Once upon a time women weren’t able to discuss their health needs – orgasms was a forbidden topic of conversation, advertising for contraception was illegal and sanitary pads were impossible to hunt down in your local store. However, luckily times have changed. Women have become more vocal about their needs, with taboo-breaking social media campaigns such as #livetweetyourperiod and also become savvier due to a rise in more female-targeted products, which give women valuable health info about themselves.

We think sexual and reproductive health shouldn’t be an afterthought to general health care, it should be taken more seriously! In light of Fertility Awareness Week this week, we wanted to shed some light on how Natural Cycles, which is programmed to spot underlying fertility issues, can help you keep a closer eye on your health so nothing gets in the way of your reproductive goals.

As you may already know, changes in temperature throughout your cycle is directly linked to what is going on in your body.  A rise in temperature indicates ovulation has occurred and a cooling of the body happens as your new cycle begins and you get your period. However, these events don’t always happen, which could be linked to your reproductive health. For instance, anovulatory cycles (no ovulation), frequent periods (short luteal phase) or excessive pain leading up to your period can all be indicators of a health issue that might need a closer look from your doctor. Here’s what to look out for!


Anovulatory cycles

Anovulatory cycles is when a women skips ovulation. Without ovulation it is impossible to get pregnant, which is why it is linked to infertility. Anovulatory cycles are common amongst women especially if you have only recently started your period, come off the pill,  on the lead up to menopause or if you are breastfeeding.


Periods still appear as normal during anovulatory cycles as your endometrial lining still sheds (estrogen breakthrough bleeding), so if a woman is not tracking her cycle, it is likely that she may not even know she has had one.

The most common cause of anovulatory cycles is Polycystic ovary syndrome (PCOS), which affects 8 to 12 percent of all women. PCOS is strongly linked to lifestyle as are the occasional anovulatory cycles, which can be caused by obesity, stress, illness, thyroid dysfunction and even travelling.

Tell tale signs of PCOS are heavy periods, acne, facial hair and excess belly fat. And if you’re tracking your cycle your cycles will appear irregular, longer than average at around 35 days and you will have a lack of temperature shifts (rise of 0.2 – 0.45C), which indicates that no ovulation occurred. The algorithm will notify you if it captures an anovulatory cycle and furthermore, if your cycles are more than 40% anovulatory it will recommend that you visit a doctor to get assessed.  



It is important to diagnose PCOS as there are simple changes that you can make to your lifestyle that can control it. Eco Watch has a great article to help women overcome PCOS through changes to their diet.


Frequent periods

Frequent periods may be caused by an abnormality in your endometrial development – the lining of your uterus – which is known as a Luteal phase defect.

The luteal phase is the stage of your menstrual cycle that occurs after ovulation and before your period starts. During this phase, progesterone causes the endometrium to thicken in order to support the implantation of a fertilised egg, however, with luteal phase defect, the lining of the uterus does not grow properly, which can make it difficult to get or stay pregnant. This can be because either your ovaries do not release enough progesterone or the lining of the uterus does not properly respond to the progesterone.

Luteal phase defect is often characterised by a short luteal phase, which can difficult to diagnose as there is no single test that can but monitoring the number of days between ovulation and your period is a good start. Natural Cycles is a useful tool, as it will notify you if it suspects such irregularities if for instance your luteal phase is often found to be shorter than 9 days long.




Painful periods

Symptoms such as severe menstrual cramps and pain during intercourse can be indicative of a condition called, Endometriosis. It is a condition that affects around 10% of women and is where uterine cells that normally shed during menstruation implant in other places in the body. The cells that continue to act like uterine cells, create scar tissue at the time of menstruation which is what causes pain and often infertility.

If you experience painful menstrual cramps, it is worth monitoring your cycle to look out for other symptoms, such as premenstrual spotting, periods lasting longer than 8 days, low luteal phase temperatures near the cover line and feeling tired throughout your cycle.

If you suspect you might be suffering from endometriosis and not just bad period pains, speak to your doctor and ask whether it could be possible. Before visiting your doctor, It is worth knowing that endometriosis takes on average 7.5 years from onset of symptoms to get a diagnosis [Ref. 1] as many doctors believe it doesn’t occur in young women. Unfortunately, there is no way of preventing endometriosis but there are ways of managing symptoms and in some cases, eradicating the disease with surgery.

So there you have it Cyclers, the reproductive organs are important to track along with your general health like your heartbeat or sleep patterns! Sex-tracking technologies, like Natural Cycles, have the power to help people take more charge of their health and communicate better with their doctors so there’s no more guessing games!  





  • Diagnosis Survey. Endometriosis UK. February 2011.



From NaturalCycles Prevention to Planning

Our NaturalCycles website is now finally finished and women can use it both as a contraception method (NC Prevention) and as a tool to get pregnant when they want to (NC Planning).

NaturalCycles web desing with beautiful natural women in nature

For the last 18 cycles, which correspond to about 1.5 years, my husband and I have been using NC Prevention as a birth control. It has been working very well for us, with usually around 10 fertile (red) days per cycle where we have to take care not to get pregnant. For those days we use a condom and for the remaining non-fertile (green) days we can enjoy not using anything. My husband says that he likes the variation, as it feels very special for the first green days after ovulation.

Fertility projection with ovulation day today

Today is my ovulation day for this cycle and probably the last time that we will use a condom in quite a long time, since as of next cycle we will switch to NC Planning and start trying to get pregnant. Our wedding anniversary is coming up on the 11th of August, which is next month, and we are going on a romantic getaway to south of Switzerland for the weekend. I am due to ovulate right after, placing our anniversary during the most fertile days in the cycle. I am a sucker for romance and I imagine it very romantic to conceive a baby on our first wedding anniversary. I realize that I might be naive thinking that things will go our way during the very first time we try, but due to my work with NaturalCycles I know exactly when I ovulate and all the details that come with it. We’ll just have to see and I will keep you posted on how it goes.

Fertility calendar with red and green days

I am also very excited to see how my temperature chart will change if I get pregnant. I will definitely notice it very early as the temperatures rise further around the time of implantation (~9 days after ovulation). I’m wondering how to tell my husband when I find out. I’d like to make some kind of romantic surprise gesture, but I’m not sure exactly what yet. Any ideas?

Exciting times are definitely ahead!

From Higgs bosons to the menstrual cycle

I am a physicist and a proud one. This despite the fact that I am a girl and look much more like Penny than Sheldon in Big Bang Theory and I have ever watched a Star Trek episode in my life. The geeky connotations aside, physics was indeed all I had wanted to do as a career from the age of 5 to 28. What made me change my mind was when we finally found the Higgs boson last summer.

I was working as a Post-doc at CERN in the ATLAS experiment and was one of the leading scientists in the Higgs to WW channel. We had been working so hard for so many months and the feeling that a discovery was near was in the air. We usually first hide the signal region until everything else has been fully understood. When ready, we “open the box” and have a peak at what’s there; background only or a signal. By the end of June 2012 we were ready to open the box and when I first saw the results, tears of joy came to my eyes. The signal was so clear and beautiful! The ambiance that day was unbeatable and a few of us stayed at CERN the entire night writing up the paper. You must understand that such a major discover only happens in particle physics once every decade or so. I was truly lucky to be part of this after only having worked at CERN for 5 years time. It was the most exciting week of my life.

Pouring champagne in the NY times

After the Higgs discovery I was filled with emptiness.

We had now confirmed the Standard Model of Particle Physics, which was established already in the 60’s, and not much else seemed to be lingering under the horizon. At the same time I had the luxury of completely turning off and enjoying my wedding in Sweden and an amazing honeymoon in Seychelles. This was the first time I had some days without being 100% focused on work and I started wondering what i now should do with my life? CERN was soon about the shut down its accelerator for some years of upgrade work and this seemed like a natural time to try something else. I wanted to take advantage of the analytical and statistical skills I’d acquired at CERN, but now to apply them to something that could be of direct use.

In the beginning of 2012, I had stopped taking hormonal contraception as I felt that after 10 years on the pill, my body needed a break. I had been searching the web for whatever natural contraception is out there that I could use instead. What I found was a disappointment; either very unserious and girly apps or the ladycomp, a German device from the 90’s with a thermometer and a simple display showing fertile and non-fertile days. Despite the steep price of $500, I ordered the ladycomp and started measuring my temperature. I rapidly discovered that this machine was not only outdated, but also shockingly inaccurate in detecting and predicting the ovulation day and the fertile window.

I read all of the relevant research and started making my own calculations using temperature only or combined with ovulation sticks. With the tools I had at CERN I could quickly make predictions that were more realistic and started following those rather than that of ladycomp. Later realizing that one can buy a basal body thermometer for only about $5 online, I got quite upset about all the money I spent on the ladycomp.

So one day last summer, when my husband and I were lying in bed trying to visualize what to do with our future and he suggested to try and do a web app such that also other women can profit from my tool, I was once again full of excitement. Some months later I quit my job at CERN and moved to Zurich to work full time on our start-up; NaturalCycles. By then I had collected data from many different women and had thoroughly validated and tested my algorithm. Today, the website (http://www.naturalcycles.com) is fully functional and all women can profit from using it either as a birth control method or to help conceive a baby.

Although I will always consider myself as a physicist and I of course miss physics and my colleagues at CERN, I am truly enjoying working with something that people and especially women can profit from and actually use on a day-to-day basis. It is about time that a modern and natural method like NaturalCycles is on the market and that women aren’t by default put on the pill or prematurely spending all their savings on IVF.