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Irregular cycle? Can I use Fertility Tracker Daysy?

onregelmatige cyclus, kan ik met een Daysy cyclus tracker meten

One of the most frequently asked questions here at Daysy NL. To answer right away, ‘Yes, you can measure with the Daysy, even if your cycle is irregular’. But first, let's see when is your natural cycle irregular? Ladies still sometimes chat in panic if their period hasn't come after 31 days because they think your cycle is ‘supposed’ to be 28 days! Fear that irregularity or PCOS will come back again and will always be like that, making it difficult or impossible to ever get pregnant.

How nice it is if you know more about this, knowledge is the key to understand your body better and what support addresses the cause so that your dreams can come true.

Cycle length also changes according to your age and stage of life. Your body but also the control of your menstrual cycle from the brain is different compared to how you started in adolescence.

Read through this info and listen to the Podcast (NL) you will be amazed at what your body is capable of. Measuring is knowing! With it, you can see how your hormonal and cycle health is doing and take those actions that will improve your cycle.


At certain periods of life, an irregular cycle can be normal and therefore harmless. Our body is not a machine, so cycle fluctuations are quite normal and usually no cause for concern. During the teenage years or during menopause, hormones are mainly responsible for these irregularities. In everyday life, stress can cause your cycle to get out of control.

An irregular cycle occurs when your cycle is permanently shorter than 21 days or longer than 35 days. A healthy cycle can fluctuate by 8 days within a year.

Regular cycle length

You have probably read that a ‘normal’ cycle lasts 28 days. In fact, almost no woman has the perfectly regular cycle of 28 days. For some, the cycle lasts 35 days, for others only 25, while for other women the cycle is a different length every month. This is quite normal and not necessarily, also not an indication of healthy fertility. Stress or illness can shorten or lengthen the cycle. As mentioned, a cycle of 23 to 35 days is perfectly acceptable. However, if your cycle is permanently shorter than 23 days or permanently longer than 35 days, it is wise to schedule an appointment with the professionals at Daysy NL and talk to your doctor.

The differences in irregularities

1. Short phase before ovulation - before a temperature rise (follicular phase)

Suppose you have ovulation on the 10th day of the cycle (which is very exceptional), this can be a signal that your body has released an immature egg. In most cases, this egg is not yet fully developed and thus infertile. If you want to get pregnant and regularly find that the first half of your cycle is very short, let us know as we would like to work with you to see how to bring more balance to your cycle progression.

2. Long phase before ovulation - before a temperature rise (follicular phase)

A long first phase of the cycle is common. With a cycle length of 35 days, the pre-ovulatory phase lasts about 21 days. Stress - even unconscious stress from within - intense exercise, a cold, travelling or an exam can prolong this phase. It does not necessarily affect your fertility. It often just means that ovulation occurs a few days later. If ovulation is later, menstruation may also be later. We see this picture more often after a flu where your body was busy recovering and delays ovulation for a while. That's clear, no time for ‘babies’ for a while even if you don't want to get pregnant your body will always put your health first.

However, are you already on the 20th day of your cycle or later and you still have red colours because your temperature hasn't risen yet? Could your pattern look like this (image below). You understand that your body could use some extra support then. Hormonal disruption goes hand in hand with symptoms physically and emotionally.

geen ovulatie, PCOS, kan ik ooit op een natuurlijke manier zwanger raken

3. Long second half of the cycle - after ovulation (luteal phase)

If ovulation has occurred, the phase after ovulation lasts between 10 and 16 days, from ovulation day to first day of menstruation. If the luteal phase lasts longer because your period is delayed and your temperatures remain higher which is the case if you are pregnant, you can get a ‘possibly pregnant’ notification if this phase lasts 18 days or longer. That is the time to take a urine pregnancy test. Dayay itself is not a pregnancy test it gives a notification based on your temperatures. When your period comes you will see your temperature already dropping the days before.

How can you tell the difference between a chance of pregnancy and not having your period just because of a longer cycle (possibly also a later ovulation)?

You can only be pregnant if you have ovulated. Then you will hit a nice rise in temperature after ovulation and your temperatures will remain stably high. You will have a lot of green days in this case.

Progesteron deficiency

natuurlijke progesteroncreme, hoe krijg ik hormonen weer in balas

If you have many red days, no gradual nice rise in temperature and little to no green days then you know you had no ovulation or late ovulation which means your period may be later but a conception could not take place or there was ovulation but the production of progesterone and the length in days to menstruation make it almost impossible for the fertilised egg to implant in the uterus and sustain the pregnancy.

Read about the hormone progesterone.

Anovulatory cycles

You may occasionally (once or twice a year) have a cycle without ovulation. In anovulatory cycles, there is no second half of the cycle. In that case, Daysy shows red and/or yellow (potentially fertile) throughout the cycle, because the device is still waiting for ovulation. You stay in the 5 fertile days before ovulation! The 5 days that sperm can maximally survive internally.

How does Daysy pick up your cycle again?

The next cycle, from the next menstruation your Daysy just picks it up again, your cycle tracker doesn't get upset. Your body may be different each cycle but Daysy can handle that just fine. She continues to indicate what your body shows.

4. Short second half of your cycle - after ovulation, after temperature rise (luteal phase)

If the time between ovulation and the first day of menstruation is shorter than 10 days, pregnancy may not come about as easily. This is called a corpus luteum insufficiency (CLI), which occurs when the yellow body (the follicle after ovulation) does not produce enough progesterone. Progesterone not only causes your basal body temperature to rise after ovulation, but also keeps the endometrium intact so that the fertilised egg can implant properly.

Actually, you can say that the rise in your BBT (basal body temperature) after ovulation AND the retention of the higher BBT before menstruation are both due to how fast, how much and whether for a long time you make the hormone Progesterone. The most optimal situation after ovulation!

Does the question remain?

How do I know which half of my cycle I am in?

Daysy allows you to track your basal body temperature and the phases of your cycle, the curve of your chart via the free DaysyDay app. You can clearly see the first and second phases by the change in temperature (see image). The Pre- and Post-ovulation baselines show the average temperatures of the first and second phase.

zijn temperaturen voor en na de ovulatie anders, meten met cyclus tracker Daysy, controleer je cyclus



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