Your Biological Clock

It’s hard to know when it's the right time to do something about checking your fertility – should you wait or do you need to do something today?

To start the Biological Clock, just use the sliders below to choose your age and the number of months you have been trying to have a baby. The Biological Clock will then tell you your chance of pregnancy leading to a live birth per month if you have no fertility problems and the chance if you have an IVF cycle at the same age. It also suggests when to seek help if you have been trying for months, with no success.

Chance of pregnancy per month - with and without IVF

The chance of pregnancy falls as a woman gets older, and the risk of miscarriage and abnormalities increases, even for people with no fertility problems. If you are having trouble becoming pregnant, the sooner you seek help, the better your chance of having a baby.


How long should I wait?

As fertility declines with age, your biological clock is the most important factor to consider.

The graph below shows the recommended time frames for trying to conceive naturally before seeking help. For example, if you are 39 years old you should consider seeking help after 5 months, and should definitely be seeking advice after 1 year.


You can check where you sit on the graph and your specific timeframes using the biological clock.

For more information about fertility and the biological clock, visit our ‘How age affects fertility’ page.


We recommend immediate referral for the following factors:
  • Experiencing extreme anxiety about fertility
  • If the woman is aged 35 years or older
  • Irregular cycles or anovulation
  • Severe sperm factor (low quality. mobility and/or quantity)
  • Previous abdo/pelvic/urogenital surgery
  • Previous STD
  • Two or more consecutive miscarriages
  • Abnormal pelvic/genital examination (woman or man)
  • Family history of menopause between 40-45 years or earlier
  • Significant systemic illness e.g. diabetes, heart disease
  • Genetic conditions, e.g. cystic fibrosis, muscular dystrophy or Huntington’s disease