Understanding the fertility window

Understanding the fertility window

For many women, trying to conceive can be a stressful time; however, learning to understand your body’s cycle and recognise signs of ovulation may help minimise some of that pressure.

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Understanding ovulation

How do I know when I am ovulating?

To calculate your ‚Äúfertile window‚ÄĚ, you need to determine what day you ovulate. To do this, you need to know the length of your menstrual cycle (which can vary from 23 to 35 days or longer). To work this out, count the number of days from the first day of your last period to the first day of bleeding in your next one. Subtract 14 days from the end of your current cycle to determine the day you ovulate.

If your cycles are irregular, or your cycle length varies from month to month, it will be difficult to calculate your ovulation date. Ovulation urine tests may be useful, but you may want to consider seeking further advice from your GP or a fertility specialist.

You may also be able to tell that ovulation is occurring if you feel a backache or tenderness in your lower abdomen. This may last a few minutes to a few hours. If you don’t usually notice these signs, you can still look out for other changes in your body.

As your menstrual cycle progresses, check your cervical mucus daily. This is the discharge that you see in your underwear or on toilet tissue. It will change in consistency, depending on where you are in your cycle. About the time of ovulation, your cervical mucus becomes clear, slippery and stretchy.


How do I chart my basal body temperature?

Following ovulation, your temperature can increase by about 0.2C (FPA 2010). You won’t feel the change, but you may be able to detect it by using a basal body temperature (BBT) thermometer. This temperature spike is an indication that you have ovulated.¬†Releasing an egg (ovulation) stimulates the production of the hormone progesterone, which raises your body temperature. You are most fertile in the two or three days before your temperature rises.

The best method of identifying when you are ovulating is to chart your temperature every morning for a few months, so you can detect a pattern and pinpoint your likely ovulation date. Then you can plan to have sex during the two to three days before the day your temperature normally rises.


When am I most fertile?

The days leading up to ovulation (when the egg is released from the ovary) are the most fertile ones in your menstrual cycle. This corresponds with the second and the beginning of the third week in a 28-day cycle with a 14-day luteal phase. During this fertile time, the egg is moving down the fallopian tube, waiting to be fertilised.

The egg can survive for 24 hours after ovulation occurs, while sperm is able to survive and fertilise an egg for two to three days in the fallopian tubes.

Intercourse frequency

We encourage couples to have unprotected intercourse every two days throughout the female’s ‚Äúfertile window‚ÄĚ.¬†This means that sperm are ready and waiting for the egg when the female ovulates. If you wait until after ovulation has occurred before you have sex, you probably will have missed the opportunity for conception that month.

How long should it take to conceive?

If you have not achieved a pregnancy after 12 months (or six months if you are aged over 35) of unprotected intercourse, you should seek advice from your GP or fertility specialist.

Tips to boost your fertility

There are a number of lifestyle changes that you can implement to maximise your chances of conception and give your baby the best start in life. To learn more, go to our Preconception care page.




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