Around 30% of fertility problems can be ascribed to the woman and 30% to the man, while in 40% of cases it is due to both partners or the cause is unknown.⁸

Fertility reduces as a woman ages. Among women in the 19-26 years age group, 92% will conceive after one year and 98% after two years. For women aged 35–39 years, 82% will conceive after one year and 90% after two years. Another way of describing this is that the chance of a successful conception in each natural menstrual cycle is nearly 20% for women under 30 years but falls to 5% in women at the age of 40.^5,9

The main issue with aging is the reduction in ovarian reserve, as the number and quality of eggs decline. As the woman gets older, conceptions are also more likely to occur with chromosomal abnormalities with increased risk of miscarriage.⁹

Sexually transmitted infections (STIs), the use of certain medicines and drugs, stress and lifestyle factors such as excessive alcohol, being overweight, smoking, and excessive exercise may be factors in both male and female infertility.⁵