Ovarian Reserve and Egg Freezing
Women are born with a set number of eggs or oocytes, usually around a million, though the number varies greatly. Many of these die off each month and many make themselves available for ovulation. If you consider that a woman might ovulate once a month for 40 years, then that would only be 480 eggs. The other 999,520 are lost.
The number that are used up each month is proportional to the number that remain. So that early in life a large number of eggs are available and lost, and towards the menopause only a few remain and so only one or two are available. It is an unfortunate fact that these later eggs are of a poorer quality.
The number of potential eggs that a woman starts with and the rate at which they are lost varies, and there is thought to be little a woman can do about this except not smoking. This means that some women will be producing good quality eggs well into their forties, whilst others have ovarian failure in their thirties, and rarely even before that.
The graph shows the normal distribution for the number eggs a woman might have at any given age. The blue line being the average, the red lines being the 10th and 90th percentiles. This shows that for two normal women in their mid thirties, one might have as many as a thousand times more eggs that the other.
There are various ways of trying to estimate a woman’s ovarian reserve. These include:
- FSH day 2 to 4 blood test: FSH is the standard blood hormone test and measures the hormone that drives the ovaries to mature the eggs. The less responsive the ovaries the higher this hormone has to work. Therefore a high FSH suggests poor ovarian reserve.
- AMH blood test: This is a newer hormone blood test and considered by most to be the most effective way of measuring ovarian reserve. AMH (Anti Mullerian Hormone) is a hormone that is released from the newly developing oocytes. A higher the level suggests more oocytes are developing and therefore a better ovarian reserve.
- Antral Follicle Count. It is possible to count the number of developing oocytes by transvaginal ultrasound scan. The Antral Follicles contain eggs that are getting ready to mature and ovulate, and therefore reflect the number of eggs in reserve. However there is a great deal of variability in this test depending on the quality of the scanning.
Whilst it is impossible to predict exactly what will happen in the future with either your ovaries or anything else, many women find these tests very useful.
What to do if you have a low ovarian reserve?
This of course depends on many factors, including your age and your desire to have children. In terms of improving your ovarian reserve, there is nothing that can be done. There is no way currently to increase the number of oocytes. You can make things worse with an unhealthy life-style, and in particular smoking. There is no point in taking vitamins or reducing your caffeine in-take if you are still smoking.
So what can you do? Don’t delay in getting pregnant. If your ovarian reserve is on the low side, then consider carefully whether putting career progress before child bearing is the best thing for you. If your reserve is low, it does not mean that you cannot conceive easily, but it is clear that your chances are reduced.
If you have been trying to conceive for some time, but have not yet managed it, then fertility treatment may be an option for you, generally this would be IVF. If the ovarian reserve is low, then some clinics might decline to treat you. However our data shows that your age is more important than your AMH, and we have had success with women with very low AMH levels. In general most couples will think it worthwhile trying a cycle of IVF, if only to get an idea of the quality of their eggs.
Dehydroepiandrosterone, or DHEA, is a steroid hormone that has been called ‘the fountain of youth hormone’. It is related to oestrogen and testosterone, and is touted as having a significant effect on the number and quality of oocytes produced for an IVF cycle. However the quality of data goes little further than anecdote, and the may be significant side-effects with its use, not least on any potential pregnancy.
The ability to freeze fertilised eggs has been around for many years, but it is only recently that routine freezing of eggs has become practical. However for many reasons this might not be appropriate for a particular woman, and unfortunately the techniques still have a limited success, with only a small percentage of frozen eggs able to fertilize properly. Also because it is a relatively new procedure then there remains some uncertainty over whether there may be an increased level of genetic anomalies in the offspring.
However despite these reservations many women choose to have their eggs frozen, in order to preserve the possibility of fertility. This may be because they are going to have treatment for cancer that will damage their ovaries, or for social reasons they are not in a position to start a family.
For many women unfortunately their ovaries are most unlikely to produce oocytes of a sufficient quality to produce a pregnancy. For these women ovum donation is the only realistic option. Pregnancy rates for ovum donation are over 60% per cycle.
There are essentially three ways to obtain donated oocytes.
- Ask a friend or relation. They will need to be in good health, with a regular menstrual cycle, a good AMH, and under 35 years. You will be asking them to go through an IVF cycle and at the end of it, giving you their eggs. Once fertilised and transferred to you, you will become the legal and physical mother. The donor will be the genetic mother, but will have no rights or responsibilities for the child.
- Altruistic Donors. Sometimes a woman will present herself as a potential egg donor.
- Ovum Donation Abroad. In some countries it is legal to pay a donor for their oocytes and the donor remains anonymous. Large clinics have been established particularly in Spain to cater for Western European clientele. The most common complaint regarding these clinics is the paucity of information available regarding the donor. There are clinics in the US, giving a large amount of detail regarding the donor. They do however charge up to ten times the fees that would be payable in Europe. I tend to recommend a clinic in Cyprus, which was established by UK based doctors. They have a UK based nurse co-ordinator who will guide you through the process. All scans and work-up are arranged with myself, and you and your partner will need to be in Cyprus for a few days.