A study has shown that most women trying to conceive will do so within 2 years. However, it may take longer depending on the age of women. A team from the US National Institute of Environmental Health Sciences in North Carolina

found that 50% of healthy women who do not conceive in the first year will do so in the second year.
Dr. Dunson, who led the research, has criticized some doctors for intervening too fast. "Only 3% of 19 to 26-year-olds, 6% of 27 to 34-year-olds and 9% of 35 to 39-year-olds failed to conceive in the second year, provided the male partner was aged fewer than 40."
He also felt that the age of the male partner was significant. He found that 28% of women failed to conceive in the first year if the male partner was over 40 and the woman was between 35-39 years. If the partner was sunder 40 years then 18% of these women were unable to conceive in the first year.
Dr. Dunson felt that the definition of fertility which is currently defined by a couple trying for 1 year should be changed