Infertility has different definitions around the world, often influenced as much by politics as by science. For example, the World Health Organisation defines a couple as infertile if they have had unprotected sex for a year without conceiving, whereas the National Institute for Clinical Excellence in the UK, which approves treatments for public funding, extends the waiting period to two years before a diagnosis is given.
On average, around 85 % of couples under 35 who have regular, unprotected sex will conceive within a year. That percentage rises to 90 % after two years but infertility is much more common than you may think. As many as 25 % of couples go through a period of infertility lasting a year or longer. Of these, it is estimated that between 10 % and 15 % of couples worldwide have a continuing problem with infertility and may need infertility treatment to start a family. In developed countries, one in six couples seek help after failing to conceive when actively trying to do so.
The first line of advice is usually to keep trying, but after two years most doctors around the world agree that investigations into the possible reasons for infertility should then be carried out. If there is a clearly identifiable medical problem with either the male or female partner, then a diagnosis of infertility can be given fairly quickly, but in many couples the cause of their infertility remains unexplained.
Identifiable causes of infertility problems are split evenly between male and female issues, with around 30 % of problems caused by each partner. A further 10 % of problems are caused by a combination of issues from both partners, while the rest cannot be attributed to either.
Age also has a significant effect on fertility levels, particularly the age of the female partner who is trying to conceive. Infertility is therefore much more common in older women. Fertility rates initially start to drop as early as the mid twenties, and fall away sharply past the age of 35. Under 35, you have a 92 % chance of becoming pregnant within two years of regular, unprotected sex, whereas by 38, your chances of becoming pregnant after three years drop to just 77 %.
The good news is that although up to 15 % of couples will have infertility problems, around 90 % of these problems can be successfully overcome by the range of infertility treatments available today.