Reviewed by Dr. Suruchi Thakore on Aug 22, 2022
There are only a few days during each menstrual cycle when you can become pregnant – the day of ovulation and the days leading up to it. This is known as your “fertile window.” Up to 50% of couples may try to conceive at the wrong time, because they don’t know when these most fertile days are1.
Trying for a baby?
Join our study and use Clearblue Ovulation Tests for free!
We're looking for women who are 18 and over, UK residents and trying to get pregnant. Other exclusions apply.
- There are only a few days each month when you can get pregnant.
- However, these days vary from woman to woman and cycle to cycle, even in “normal” cycles.
- Accurately predicting ovulation will help you maximize your chances of getting pregnant naturally.
- Hormonal changes control ovulation. The surge of a hormone called LH (luteinising hormone) triggers ovulation which occurs 24-36 hours prior to ovulation.
- Clearblue Ovulation Tests are at least 99% accurate at detecting the LH surge, to help you get pregnant faster.
- An important study showed that 77% more women became pregnant when they identified their fertile window (using a digital ovulation test) than those who simply had regular intercourse2
- If you are not able to detect ovulation regularly, this could be a sign to seek medical attention and assistance with getting pregnant.
Most menstrual cycles are not "average"
As many as one in two couples may be trying to conceive at the wrong time, because they don’t know when their most fertile days are1. A study among women trying to get pregnant found that only 13% correctly estimated their ovulation day, and only 55% of women estimated their day of ovulation within their 6 day fertile window (five days prior to + the day of ovulation)3.
It is difficult to be sure when you are ovulating because most women’s cycles are not "average".
Many women believe that ovulation occurs on day 13 or 14 of their cycle. This is based on a typical cycle of 28 days, but this varies between women, and between cycles. In fact, 46% of menstrual cycles vary by seven or more days4. This has a significant impact on the timing of ovulation from one cycle to the next. It is therefore often difficult for women to accurately predict their fertile days during each cycle.
Professor Bill Ledger, Fertility Specialist
Everyone is different and women cannot rely on population averages to understand their own fertility. Understanding when they ovulate is one of the easiest steps that women can take to understanding their fertility, and ovulation tests are the easiest way for women to accurately predict when they will ovulate. Conventional LH tests give couples one to two days advanced warning of ovulation. Clearblue have also developed more advanced products that give women even more information.
Your personal cycle is controlled by your individual hormone levels
The menstrual cycle is controlled by hormones which change throughout the menstrual cycle and control ovulation. The hormones that are most important in developing an egg and getting pregnant are:
- Estrogen: is made by the growing egg. Estrogen gradually rises in the early stage of the menstrual cycle leading up to ovulation. This increase also changes the cervical mucus, which creates a favorable environment for sperm.
- Luteinising Hormone (LH): is created by the brain in response to estrogen and surges 24-36 hours before ovulation (the release of the egg), making it the best predictor of ovulation.
The LH surge is the most accurate predictor of ovulation
There are a variety of methods that may help women identify their ovulation day, including calendar charting, body basal temperature and tracking ovulation symptoms. However, they vary in their ease of use and accuracy.
Clearblue’s Ovulation Calendar Tracker can help you track your cycle and get to know your body as you plan to get pregnant. However, the calendar method has been found to predict the correct fertile days in only one third of cycles5, so they are best used in tandem with a more accurate method like ovulation tests.
No matter how your cycle varies month to month, the LH surge is the most accurate predictor of ovulation.
Get pregnant faster: use an ovulation test
- Accurate: they are at least 99% accurate at detecting the LH surge to accurately pinpoint the best two days to conceive.
- Simple to use: simply test with the first urine of the day when the hormones are most concentrated. Digital tests provide easy read results. Find out more about how to use ovulation tests.
- Keep the magic in “BabyDancing”: carrying out recommendations to have intercourse regularly throughout the cycle can be emotionally demanding and can quickly lead to a ‘mechanical’ approach to intercourse whilst trying to conceive. Ovulation tests takes the guess work out of timing intercourse, to help you keep the fun in getting pregnant naturally.
- Confirm you are ovulating normally: Confirming this early on is helpful, as you can seek the help of a healthcare professional earlier and it can help the doctor identify whether there is a medical issue and give you the appropriate advice.
- Help you get pregnant faster: A study showed women using ovulation tests took on average 10% less time to become pregnant than women advised to have regular intercourse2.
Professor Bill Ledger, Fertility Specialist
Most women’s cycles are not “average”
Everyone is different and women cannot rely on population averages to understand their own fertility. Understanding when they ovulate is one of the easiest steps that women can take to understanding their fertility, and ovulation tests are the easiest way for women to accurately predict when they will ovulate. Your personal cycle is controlled by your individual hormone levels.
Get pregnant faster: use an ovulation test.
I would encourage all women planning to get pregnant to consider using ovulation tests – the improved understanding of their bodies is emotionally reassuring, and it will help improve their chances of achieving pregnancy more quickly.
Advanced Digital Ovulation Test
- 1. Johnson SR., et al. Hum. Repro. (2011) 26: i236.
- 2. Tiplady S., et al. Human Reproduction (2013) 28(1): 138-151. 210 women. Not statistically significant for conception rates.
- 3. Zinaman M., et al. Current Medical Research and Opinion. (2012) 28: 1–6.
- 4. Creinin MD., et al. Contraception (2004) 70:289-92.
- 5. Ellis JE., et al. Human Reproduction (2011) 26: i76
Read More
Predict your periods, track your cycles, or try for a baby
With the Clearblue® Period & Cycle Tracker app.
App images for illustration purposes only.
Advanced Digital Ovulation Test
In every cycle there are only a few days when a woman can conceive, so having sex on these days is very important if you are trying to get pregnant. The Clearblue® Advanced Digital Ovulation Test is the first and ONLY test that typically identifies 4 or more fertile days each cycle.
Get pregnant naturally
Ovulation tests are accurate and simple to use.