Your chances of conceiving naturally

Most common questions fertility specialists get asked:

“How long will it take to get pregnant?”


“What can we do to increase our chances of getting pregnant?”


“What are the odds that I will get pregnant this month?”

Some answers: 

On average 15-25%  of couples trying to conceive will be successful per month.

Monthly chance of conceiving naturally
Female age Chance
18-25 years 20-25 %
26-35 years 15-20%
36-40 years 10%
41-42 years 5%
43-45 years 2%
> 45 years 1%


Many statistical studies have been performed looking at the odds of conception over a time period. The results can be expressed in the table below:

As demonstrated in the chart above, around 80 percent of couples fall pregnant within 12 months of trying, and more than 85 percent will fall pregnant by 18 months. The older the couple, the more difficult it can become. Female age is the most important factor when considering the probability of conception. Comparatively for men, age usually doesn’t become an important issue until around 45 years of age.

For both men and women, if you are under the age of 35, in good health and having regular unprotected sex your chances of conceiving within 6 to 12 months are pretty good.

How to optimise your chances

Knowing your cycle and day of ovulation (release of the egg), plus having frequent sex, especially at your most fertile time will help maximise your chances of falling pregnant.

If you have a reasonably regular menstrual cycle you can track your ovulation by measuring the basal body temperature method, or by testing your urine for a luteinising hormone (LH) surge.

The LH surge occurs 24 to 36 hours prior to ovulation. It causes the final maturation and release of the egg (around mid-cycle). Being aware of your most fertile time will allow you to accurately plan when to have sexual intercourse for the best chances of natural conception.

If your cycle is slightly irregular and you are unsure of when you may be ovulating then having sex every third day could help with your chances of conceiving.

What can affect your chances of getting pregnant?

Many factors come into play when trying to fall pregnant:

  • Increasing female age: Chances of falling pregnant naturally reduces as your age increases each year. For example, at 40 years of age, you have approximately a 10 percent chance of conceiving, this drops to five percent by the age of 42.
  • Frequency of sexual intercourse: The less often you have sex, the less likely the chance of conceiving.
  • The regularity of the menstrual cycle: Most menstrual cycles are monthly, giving 12 episodes of ovulation each year. If sex is timed around ovulation then the ovulated egg has 12 chances of meeting the sperm each year. If menstrual cycles are infrequent or irregular then the chances of  the egg and sperm meeting and fertilising will be less, thus reducing the odds of conceiving.
  • Poor lifestyle factors: Studies have demonstrated reduced fertility in couples who smoke, consume excessive amounts of alcohol and who have a body mass index (BMI) greater than 30.
  • The length of time a couple has been trying: Chances of falling pregnant reduces over time, with the most fertile of couples conceiving more quickly, while the lesser fertile couples taking longer to conceive.

For couples who have been trying to conceive for 12 months or longer it is recommended they seek fertility advice from a doctor or fertility specialist.


  1. Jansen R. 1997. Getting Pregnant. p1-20. Allen and Unwin
  2. Balen AH et al. 2007. Impact of obesity on female reproductive health. Human fertility Dec; 10(4):195-206 British fertility Society, policy and Practise Guidelines
  3. American Society of reproductive medicine 2012. Age and Fertility. A guide for patients. P1-16
  4. Wilcox AJ, Weinbert CR, Baird D. Timing of sexual intercourse in relation to ovulation. New England J. 1995(333); 1517-1521