the quality of a woman's eggs deteriorates with age and this is something science can do nothing about. Women are born with a certain number of 'eggs' or oocytes and their quality starts declining rapidly after the woman turns 35. There's nothing that medical science can do to halt the deterioration of these eggs. The age of the female - and the male as well - remains critical when it comes to having babies. And women the world over are delaying maternity for their careers, or for other reasons which is giving rise to infertility. At least 10 to 15 per cent of couples worldwide (or about 70 million) are infertile. There is an estimated 15 to 20 per cent of couples in Singapore who are infertile, with only half of these couples seeking medical advice for their situation. There are still too many variables when it comes to assisted reproductive techniques. It can depend on the patient - her response to stimulation, genetics and infertility profile; the doctor's diagnosis, experience and treatment applied; the drugs and devices for controlled ovarian stimulation (COS); the retrieval process of the egg; the embryologist's experience; the laboratory facilities and technologies utilised; the transfer technique and so on.