How to pinpoint ovulation time?

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Ovulation is the key event that happens only once during a woman’s menstrual cycle. This is when a mature egg is released from the ovary due to a surge in the Luteinising Hormone (LH). Upon release, the egg travels to the fallopian tube, where it may be fertilised by a sperm.

Since an egg lives only 12-24 hours after leaving the ovary, and sperm is active for two to three days, getting the right timing is critical. To improve your chance of falling pregnant, IVF Australia recommends having sex every two days throughout the female’s fertile window.

That leads us to the question: “When is your fertility window?”

When is your ovulation day and fertility window?

To answer this question, we first need to know the length of your menstrual cycle. Some women have shorter and some have longer cycles, but on average, a cycle is 28 days.

To work out the length of your cycle, record the first day of your period as day 1 and the day before your next period as the last day.

If you have a regular cycle of 28 days, you will most likely ovulate around day 14. The likelihood of fertilisation is highest between days 11 and 14.

If your average cycle is not 28 days, subtract 14 days from the end of your current cycle to get an approximate ovulation day.

According to The Fertility Society of Australia, the “fertility window” is typically five days before ovulation through to the day of ovulation, and the highest likelihood of conceiving is in the three days leading up to and including ovulation.

IVFAustralia’s Ovulation Calculator is a great tool to help you estimate your fertile window. 

Are there any signs of ovulation?

  • A few days before ovulation, the vaginal mucus becomes clear and slippery (best physical sign before ovulation)
  • Possibly light blood or spotting during ovulation
  • Possibly light pain near the ovaries
  • Possibly breast tenderness
  • Possibly increased sex drive

Note that these signs only occur in some women and are not the most reliable method to predict ovulation. 

What can affect ovulation?

Ovulation is sensitive to a number of things, including stress, illness and disruption of normal routines.

Although we will get to tracking ovulation, always bear in mind that stressing out over tracking habits can potentially change your cycle! 

How to track ovulation?

In the old days, a basal thermometer is used every morning to track the half degree temperature rise after ovulation. This method is not very accurate because other factors like catching a cold could also affect temperature. Saliva ovulation kits are similarly difficult to interpret. On top of that, having to collect samples every day is tedious and adds to the stress that may affect cycles.

Urine ovulation kits

Urine ovulation kits detect the LH surge prior to ovulation. They are convenient and reasonably accurate. Highly sensitive urinary LH kits could detect low LH concentrations. To use these kits, you start testing your urine each day four days before the estimated ovulation day. Once the test turns positive, you can expect to ovulate within 48 hours. However, it is worth noting that “luteinised unruptured follicle syndrome” occurs in 10.7% of menstrual cycles in fertile women, in which no egg is released despite a normal LH surge.

Blood test and Ultrasound test

A combination of blood tests and ultrasounds can give you a very accurate overview of your cycle and fertility. Unlike home ovulation tests, these tests are performed in a fertility clinic and measure a range of female hormones: estrogen, progesterone and LH throughout your cycle.

The ultrasounds can also visually confirm follicular growth leading up to an ovulation. They are recognized as the standard reference examination for ovulation detection. However, blood and ultrasound tests are less convenient and are mainly used as a step in artificial reproductive methods


The best way to pinpoint your ovulation depends on your cycle. If you have a regular cycle, having sex every second day during your fertility window should give you the best chance. If your cycle is irregular, you could consider tracking methods and seeking further advice from a GP or fertility specialist.