to female disorders, 20% of male origin, 27% resulting from abnormalities in both man and woman, while 15% of the cases could not be attributed to either partner (de Kretser, 1997). According to Evers (2002), five types of disorders leading to infertility have been recognised. They are summarised in Table 1.
Ovulation disturbances are a common cause of subfertility in women (Snick et al., 1997). Ovulation problems due to disturbances in reproductive hormones present themselves as irregular or absent menstrual periods viz., oligomenorrhoea or amenorrhoea (Hamilton-Fairley and Taylor, 2003). Hormonal balance governing the ovarian cycle is a critical factor in female fertility. Several factors including stressful lifestyles, extremes in body weight, diet, certain hormonal diseases (e.g., pituitary gland tumours) and endocrine disrupting chemicals, such as PCBs and some pesticides can impact a womans hormonal balance and, thereby, the ovulatory pattern (Farr et al., 2004). Age is another important factor that influences female fertility (Maheshwari et al., 2008) which starts to decline around the mean age of 37.5 years (Hourvitz, 2009). Fecundity of a woman declines with age because of the loss of follicles from the ovary. Advancing age could lead to infertility in a woman on account of poor oocyte quality related to a higher number of chromosomal aberrations and cytoplasmic malformations in the oocytes (Laufer et al., 2004). Furthermore, advancing maternal age could adversely influence the capacity of the oocyte to sustain early embryo development vis-a-vis biochemical and molecular processes promoting fertilisation, embryo formation and successful development to term (Gilchrist et al., 2008);
Male infertility resulting in the reduced ability of the female partner to become pregnant is usually on account of low sperm counts, obstructive azoospermia or primary spermatogenic failure including reduced motility and/or abnormal morphology of sperm (Snick et al., 1997);