There are two important factors to consider when judging a couple’s fertility: the age of the female partner AND the length of time a couple has been sexually active without using an effective form of contraception.
The monthly chance of pregnancy (called fecundity) depends on the age of the female partner and decreases as a woman ages (read more below). For instance, a woman in her twenties has 25 percent fecundity, but as she approaches her 40s fecundity is approximately 5 percent.
Furthermore, the chances of getting pregnant are highest during the first 3-6 months after discontinuing contraception (i.e. stopping the birth control pill). After one unsuccessful year, irrespective of female age, remaining couples have a much smaller chance of pregnancy without treatment, less than 3 percent per cycle (assuming the woman ovulates, sperm are present, and at least one fallopian tube is open).
The cause of infertility may be identified, but remains “unexplained” in approximately 20 percent of couples, meaning that a specific cause for their infertility is unknown. However, many successfully achieve pregnancy with treatment – often with simple interventions.