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Timing for conception


When planning a baby, a couple needs to make sure that they are having regular intercourse and that it is at the correct time in a woman's menstrual cycle. Awareness of your fertility window increases your chances of conception.

The fertility window is the days in the menstrual cycle when conception is possible. This is from the day the egg is released (ovulation) and the five days prior.

The reason for this is that sperm can survive for up to five days and the egg for only 12-24 hours.  We recommend tracking your cycles and aiming for intercourse at least every second day during this time.

If you have irregular cycles, we recommend you aim for intercourse every second to third day.

How to track your cycle

Working out your fertility window can be helped by tracking your menstrual cycle. You can simply mark your periods on a calendar or try some of the many apps available online (none of which are proven or endorsed by Fertility PLUS).

The average menstrual cycle is 28-35 days. Ovulation usually occurs 14 days prior to your period starting. We recommend you track two to three cycles and work out the average length of your cycle. From this you can work out the average time you are likely to ovulate.

  • If your cycle is 28 days, ovulation should occur on day 14. Therefore aim to have regular intercourse from 10 days after your period has started.
  • If your period is 35 days, then ovulation should occur at 21 days and intercourse should be from 17 days after your period started. 


There are bodily signs that change over the month that can help you to identify if you have ovulated.

Signs of ovulation

  • Change in cervical mucus: Just before ovulation your cervical mucus changes to become clear and slippery, this is to allow the sperm to pass through the cervix. After ovulation the mucus becomes thicker and changes to a white/yellow colour, and hinders sperm transport.
  • Changes in bodily hormones: Measuring a woman's luteinising hormone (LH) can help indicate ovulation, as the LH increases one to two days prior to ovulation. LH can be measured in the urine and is the basis of commercial ovulation kits. These are generally used for five to six days prior to your expected ovulation day. Commercial ovulation kits should be used with caution as there is limited evidence of the effectiveness in improving fertility outcomes.
  • Changes in body temperature: Measuring your 'basal temperature' has been used to help identify if ovulation has occurred. Fertility PLUS does not recommend this technique as it is often inaccurate and can increase your stress levels. It is a retrospective test, so once your temperature has increased, you have already ovulated, potentially missing your fertility opportunity.