How to tell you are ovulating
Your body goes through certain changes when you ovulate.
- Hormone levels change
- Your temperature increases slightly
- You have an increase in cervical mucus
- Your saliva pattern changes.
These might be unnoticeable to you as you go about your daily life but if you set about ‘watching’ closely for these they can help you can work when you ovulate. You may find some of these methods easier to track or more reliable than others.
Most of the apps or tools on the market use one or more of the methods below. If you’re using an app, it’s important to use one that tells you how it calculates your fertile window. Be wary of apps that only use dates as this does not give very accurate results.
In this document we’ve listed some of the most popular apps and tools available. This is not an endorsement. Tommy’s does not endorse specific products or services.
Measuring the level of luteinising hormone (LH) in urine
There is always a small amount of a hormone called the luteinising hormone (LH) in your urine but it increases dramatically once a month around the time you ovulate. This increase is known as the LH surge.
Ovulation test kits pinpoint ovulation by measuring when this happens, giving you a ‘fertile window’ so you can make sure you have sex (and therefore sperm in your system to meet the egg) at this point.
Some tests also measure another hormone called estrone-3-glucuronide (E3G). This is produced when estrogen breaks down in your body and accumulates in your urine around the time you are ovulating.
Examples of urine-based ovulation predictor kit brands include:
- Clear and simple (measures LH)
- Clearblue (measures LH and E3G)
- First response (measures LH)
- One Step (measures LH)
- Supermarket/pharmacy own brands (mainly measure LH).
Do ovulation predictor tools/kits work with PCOS or other fertility issues?
For the majority of people ovulation kits work well, but in some cases, for example in people with an anovulatory disorder (where you do not ovulate) the surge in LH may happen without ovulation. Talk to your GP if you have been testing your hormone levels for a few months and the results seem odd or are not showing ovulation.
Ovulation predictor tools may not be suitable if you have a known fertility issue that affects your menstrual cycle, such as polycystic ovary syndrome (PCOS). This is because this condition affects your hormones, so you may not get an accurate reading. Talk to your GP if you have PCOS and want to get pregnant.
Measuring your basal body temperature (temperature method)
Your basal body temperature is the temperature at which your body rests. This temperature is a bit lower than your “normal” temperature. It increases slightly when/after you ovulate.
If you track the increase over a few months you may be able to predict when you are next about to ovulate. However, it should be combined with other methods, by itself it is not recommended as a reliable way of telling whether you are ovulating.
- It needs to be taken when you are most rested (just after you wake up).
- It should be taken the same time every day (so you might need to set your weekend alarm to the same time as weekdays).
- You need a very accurate basal thermometer.
- It tells you after you have ovulated (too late for the sperm to be in your system).
Taking your temperature in this very exact way every morning can be tricky and because of this there is a danger of inaccuracy.
There are a number of apps listed below that allow you to record BBT.
There is one tool called Ovusense that links a sensor that you place in your vagina to an app. This allows it to track your temperature very accurately and it claims to detect ovulation even for women who have PCOS. It is an expensive initial outlay however and we could only find one example of this type of tool.
Tracking the dates of your period (calendar method/rhythm method)
There are many apps that take your last period start and end dates and forecast your fertility based on these
You normally have a dashboard that displays your cycle. After using it for a while the apps learns your personal pattern and hope to improve their forecast with each cycle.
Using this method alone is not recommended as it is not very accurate, even for those with a regular cycle. It’s not uncommon for women with a regular cycle to have periods that vary by a few days each time.
Most of the apps (see below) that are available combine the calendar method with another, such as measuring your temperature or tracking cervical mucus changes.
Cervical mucus changes (cervical mucus method)
The cervical mucus method is all about examining your cervical mucus (vaginal discharge) to track its consistency. Your cervical mucus changes in amount and consistency throughout your cycle.
When you are ovulating the cervical mucus changes to become more wet and stretchy to help sperm move easily through the cervix into the uterus.
Getting to know your cervical mucus means becoming comfortable with looking at and touching your vaginal discharge.
The apps that track cervical mucus don’t actually check the mucus for you but they do help you by logging the consistency and tracking changes over time, which helps you become more aware of your cycle.
Most apps that track cervical mucus also track other symptoms.
Saliva ovulation predictor kits
These test for increased levels of oestrogen and salt in the saliva, which happens when you’re close to ovulating. You put some of your saliva on a glass slide, allow it to dry and look at the pattern if it makes. If it forms a fern-shaped pattern (known as saliva ferning) you may be ovulating.
Examples of saliva ovulations predictor brands include:
- Maybe Baby.
These are some of the most popular (and free) apps available that track multiple signs of ovulation
All of these apps start with the calendar method but can also accept and use your data from basal body temperature tests, cervical mucus changes and urine-based ovulation test results.
- Glow Fertility
- Kindara Fertility and Ovulation
- Ovia Fertility and Ovulation
- Clearblue Connected Ovulation Test System.
Johnson S et al. (2018) Can apps and calendar methods predict ovulation with accuracy? Current Medical Research and Opinion, 34:9,1587-1594, DOI: 10.1080/03007995.2018.1475348
[NS Choices. Irregular periods https://www.nhs.uk/conditions/irregular-periods/ (Page last reviewed: 09/04/2018. Next review due: 09/04/2021)
NICE (2013). Fertility problems: assessment and treatment. National Institute for health and care excellence https://www.nice.org.uk/guidance/cg156
Hsiu-Wei Su,et al (2017) Detection of ovulation, a review of currently available methods Bioengineering and translational medicine 2017 Sep; 2(3): 238–246.
Grimes DA, et al. (2012) Fertility awareness-based methods for contraception Cochrane Database of Systematic Reviews 2004, Issue 4. Art. No.: CD004860.DOI: 10.1002/14651858.CD004860.pub2Hide details
ℹLast reviewed on March 14th, 2019. Next review date March 14th, 2022.