It is estimated one in six couples in Australia will struggle to get pregnant.
For some, the reason will be explicit.
Better Health Victoria identifies the most common causes of infertility in women to be problems with fallopian tubes, ovulation disorders, endometriosis, fibroids, pelvic inflammatory disease or polycystic ovarian syndrome.
For men, issues such as a low sperm count, blocked vas deferens tubes, genetic diseases or abnormally shaped sperm can prevent them from impregnating their partner.
But for almost one in three couples who have not fallen pregnant after a year of trying, a diagnosis of unexplained infertility is given.