Infertility is defined as the inability to conceive naturally after one year of regular unprotected intercourse. Most couples do not have absolute infertility but subfertility with a reduced chance of conception in each cycle due to one or more factors. Subfertility has major clinical and social implications and affects approximately thirteen to fifteen per cent of couples worldwide. In the United Kingdom, one in six to seven couples complain of infertility. Half of these couples will conceive either spontaneously or with relatively simple advice or treatment. However, eight per cent of the population remain subfertile and require more complex treatment with assisted reproductive techniques (ART) [1].