About one in six couples experience difficulty in achieving conception at some stage during their reproductive years. For some, this is temporary and pregnancy ensues spontaneously after a variable period of trying. However, there are others who can only become pregnant through medical intervention. Infertility is common, and most people will not find it hard to remember friends, relatives and/or other acquaintances with such problems. Not only is infertility common but the list of possible causes is quite extensive and to many this may initially appear intimidating. However, for conception to be possible, adequate numbers of good quality spermatozoa must be produced in the testes and delivered to the vagina at the right time in a woman's menstrual (ovarian) cycle. Conditions must be favourable for enough of these spermatozoa to ascend the female genital tract and arrive at the site of fertilization in the fallopian tube. They should be functionally adequate for the task of breaking through the cells that surround the oocyte to enable one of them to fertilize the oocyte. The fertilized egg should develop normally and implant successfully when it arrives at the uterine cavity as an embryo. Difficulty with conception will be experienced if any factor prevents the successful completion of these events.

It is estimated that 80 out of 100 couples are able to achieve pregnancy within one year of having regular sexual intercourse without contraceptives.