IVF is the original 'test-tube' baby technique, in which eggs collected from the female partner are fertilised in the laboratory. It was developed more than 30 years ago for the treatment of women with damaged fallopian tubes, and this remains an important reason for treatment today. However, it is also used in cases where a woman has endometriosis, the male partner has poor quality sperm, or when the cause of infertility is unknown.
What does IVF treatment involve?
IVF treatment consists of a sequence of procedures known as the 'treatment cycle'.
Hormone therapy is used to stimulate the development of several follicles in the ovary. These are collected as eggs, which are then fertilised in a test-tube ('in vitro') to create several embryos.
After two to five days in an incubator the embryos are carefully checked using a well-established grading system. The best one (or insome cases two) are transferred through the vagina to the uterus, where it is hoped that implantation will occur so that pregnancy can begin.
In some cases, the alternative to embryo transfer on day 2 or 3 is blastocyst culture and transfer.
However, in IVF as in natural conception, not every embryo implants to become a pregnancy, which is why surplus embryos are sometimes frozen - so that a subsequent Frozen Embryo Transfer might be tried if the first one fails.
Find out more about the IVF treatment stages.