In general, about 84% of couples will conceive within 1 year if they do not use contraception and have regular sexual intercourse. Of those who do not conceive in the first year, about half will do so in the second year. Thus 92% would achieve pregnancy in two years.
People who are concerned about their fertility should be informed that female fertility declines with age, but that the effect of age on male fertility is less clear. With regular unprotected sexual intercourse, 94% of fertile women aged 35 years, and 77% of those aged 38 years, will conceive after 3 years.
Sexual intercourse every 2 to 3 days optimizes the chance of pregnancy. Timing intercourse to coincide with ovulation will improve chances of success but may add on to the ‘stress’ and hence this can affect chances adversely.