As more couples delay starting a family in order to establish a career and gain financial security, there has been an increase in the mean age at which both women and men first present with infertility. Many couples have the unrealistic expectation that assisted reproduction treatments (ART) will assist them overcome their natural decline in fecundity. In women over 40 years pregnancies are associated with increased risks of premature birth, congenital malformations and medical complications of pregnancy and delivery. 

The major factors leading to a reduced chance of a successful pregnancy in older women are a decrease in the quantity and quality of the remaining oocytes as well as the effects of other pelvic disease such as endometriosis and fibroids. All these factors not only reduce the probability of a spontaneous pregnancy but also increase the chance of early pregnancy loss.  Markers of oocyte number include early follicular phase FSH, AMH and antral follicle number seen in a pelvic ultrasound scan. Oocyte quality and specifically aneuploidy of the oocyte cannot be assessed in vivo but is observed during ART in poorer rates of fertilization and early embryo growth in vitro. 

Older men also have decrease in fecundity. Compared with men age 25, men older than 45 years are more than four times more likely not to achieve a pregnancy in one year.  This is related to hypogonadism, sexual dysfunction, effects of the metabolic syndrome as well as altered gene expression associated with aging, all leading to deceased sperm quantity and quality. This may be reflected in increased in sperm DNA fragmentation. Recent studies show an increased risk of autism and childhood cancers in the offspring of older men.

Investigation of infertility may not identify an obvious cause and a significant proportion of older couples are described as having unexplained infertility. In this situation several management options are available. When a woman is more than 40 years old the current literature supports that IVF gives the best chance of a successful pregnancy. Attempting other treatments first delays the application and hence reduces chance of success with IVF.