One of the things that doctors want to find out about egg donors is how good their potential egg supply is, known as the ovarian reserve, and how responsive they are likely to be to the drugs that stimulate egg development. Understanding this enables the doctors to modify and tailor the egg donation treatment for each individual donor, which minimises the likelihood of over stimulation for the donor yet maximising the chances of a successful outcome.
Because no one test on its own gives a complete picture, fertility specialists will use a combination of tests to give a broad overview of the fertility status of an egg donor. These are:
- Anti-Müllerian Hormone (AMH) levels (a blood test)
- The Antral Follicle Count (AFC) (a scan)
- Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH) (a blood test)
Anti-Müllerian Hormone (AMH) Test
Anti-Müllerian Hormone (AMH) is a hormone produced by ovarian follicles that are at an early stage of development in the ovary. It is not produced by follicles that have grown beyond a certain size – only in those that have yet to grow. The hormone is measured by a simple blood test taken at any time in the menstrual cycle and gives a good indication of the ovarian reserve.
The hormone level is measured in picomoles per litre (pmol/l) of blood, with the normal range being 14.28 – 48.55 pmol/l. With egg donation, each clinic has a lower limit for accepting egg donors. As women get older AMH levels drop, but it is still perfectly possible for someone in their late 30s or early 40s to have a high AMH. Equally, an egg donor in their early 20s might be found to have a low AMH.
If an egg donor has a low AMH level, this might mean that putting her through an egg donation cycle is not in her, or the recipient’s, best interests as the amount of medication she would need for the cycle would be high, while the chance of a successful outcome of egg donation for the recipient couple is low.
It is important to point out that these AMH levels are taken to give an indication of a successful outcome with Assisted Conception. A low AMH does not mean that a woman would not be able to conceive naturally. It is just that with a combination of a low hormone level and IVF, the chances are reduced and it might be something that a donor should take into account when planning her own natural pregnancy.
Antral Follicle Count (AFC) Test
The Antral Follicle Count helps in assessing a donor’s ovarian reserve and her likely response to ovarian stimulation. Once an ovarian follicle has developed to a certain stage a fluid filled cavity, called an antrum, forms within it. At this stage it becomes known as an ‘Antral Follicle’. Using a vaginal ultrasound scan the number of these antral follicles in both ovaries can be counted, giving the ‘Antral Follicle Count’. The antral follicle count is a good predictor of the number of mature follicles that can be stimulated during the egg donation treatment process.
Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH) test
This combined blood test for levels of Follicle Stimulating Hormone and Luteinising Hormone is usually done on Days 2-6 of the menstrual cycle. FSH is produced by the pituitary gland in the brain and stimulates the follicles in the ovaries to develop. As the eggs mature the ovaries release oestrogen. If the brain senses that there is not enough oestrogen in the blood then the pituitary gland will release higher levels of FSH in order to further stimulate the ovaries to develop and release eggs. High levels of FSH in the blood early on in a woman’s menstrual cycle can therefore suggest a lower ovarian reserve.
Luteinising Hormone (LH) is another hormone produced by the pituitary gland in the brain, which stimulates ovulation to take place. Doctors often look at the relative proportions of FSH to LH.