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. As many as one in two couples may be trying to conceive at the wrong time, because they don’t know when these most fertile days are1.

  • 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 regular cycles.
  • Accurately predicting ovulation will help you maximise 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 days (using a digital ovulation test) than those who simply had regular intercourse2
  • If you are not ovulating regularly, identifying this early on is helpful to get appropriate medical attention.

Most women’s 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 amongst 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 fertile window (six days – five days prior to and 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.
Your personal cycle is controlled by your individual hormone levels


Your personal cycle is controlled by your individual hormone levels

The menstrual cycle is controlled by hormones which change throughout the menstrual cycle and, amongst other things, control ovulation. Particularly important for understanding when you can get pregnant are:

  • Estrogen: this gradually rises in the early stage of the woman’s cycle in the days leading up to ovulation. This increase also changes the cervical mucus, which creates a favourable environment for sperm.
  • Luteneinising Hormone (LH) surges 24-36 hours before ovulation (the release of the egg), making it the best predictor of ovulation.

Typical hormone levels during the menstrual cycle

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

I would encourage all women planning to get pregnant to use ovulation tests – the improved understanding of their bodies is emotionally reassuring, and it will help improve their chances of achieving pregnancy more quickly.


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