In vitro fertilisation (IVF)
What is IVF?
IVF stands for in vitro fertilisation. In vitro literally means 'in glass' and with this form of assisted conception, fertilisation takes place in a glass (or more commonly, plastic) dish in the laboratory. (At one early stage, scientists used test tubes for fertilisation, hence the term "test tube baby".) Any assisted conception procedure where fertilisation takes place outside the body is a form of IVF.
IVF was originally devised to overcome infertility caused by blocked or absent fallopian tubes. Today, IVF is used to treat many more reproductive problems, including irregular ovulation, low sperm count or motility, and unexplained infertility.
How IVF works
Depending on a woman's age, anywhere between 1 and 30 follicles, known as 'recruits', will begin to develop in each menstrual cycle. Whatever her age though, only one of these developing follicles will dominate and ovulate at the level of the hormone FSH that a woman produces naturally.
With IVF, the goal is to keep the level of FSH constant, and thus to encourage more of the recruits to develop mature eggs, which are collected surgically under vaginal ultrasound guidance.
The eggs are then fertilised in the laboratory, cultured for several days, and then one, or rarely two embryos are transferred back into the woman's uterus. If there are additional embryos, they may be frozen and stored for later use.
The steps in an IVF cycle are:
- Stimulating the ovaries with injections of FSH
- Preventing premature ovulation (the LH surge) by shutting down communication between the brain and the ovaries, so that the eggs are not lost before they can be collected
- 'Triggering' ovulation by replacing the LH surge at mid cycle with an injection of hCG
- Collecting the eggs and sperm
- Culturing embryos in the laboratory
- Transferring the embryo/s
- Supporting the endometrium in the luteal phase with hCG or progesterone