The fertilisation of ovum outside the body, also known as extra-corporeal fertilisation. This technique involves a mature egg being removed from the ovary (using a long hollow needle inserted through a laparoscope) and being fertilised under carefully controlled conditions in the laboratory. The fertilised ovum is returned to the woman's uterus at the four - or eight-cell stage, via a fine plastic tube inserted through the cervix. If the timing is right, the fertilised egg will implant in the lining of the womb and develop in the same way as a naturally fertilised egg. It is a delicate and complex procedure with no guarantees of success. There is a risk of spontaneous abortion within the first twelve weeks of gestation but generally around 25 percent of women who receive extra-corporeal fertilisation have successful pregnancies. There have been many such births since the first 'test tube baby' was conceived and born as a result of extra-corporeal fertilisation in 1978.