Causes of Infertility. There are many different causes of infertility, and often there are several infertility causes in one couple. These include: Male factor infertility. In about 25-40 percent of couples, a problem with the sperm is the cause of the infertility. The problem may be the number of sperm, the shape of the sperm, or their ability Lifetime primary infertility was defined based on 1 of 2 contraception scenarios immediately after marriage to find experience of infertility despite 1 year of unprotected intercourse. The term “current primary infertility” designated a woman who, in addition to meeting the definition of lifetime infertility, had been unable to conceive up to the study time. However, these estimates show that primary infertility, or childlessness, remains relatively rare, with rates between 1-10% in women aged 25-49. In contrast, the percentage of women experiencing secondary infertility, or an inability to produce a live birth after at least one previous birth, ranges from 9-38% (Rutstein and Shah, 2004).