Ovarian reserve and the chance of success
It has been widely proposed that the chance of success in IVF can be best predicted by a measurement of 'ovarian reserve'. How can that best be done - and why are experts excited about the hormone AMH?
The huge databases of the UK and American authorities leave no doubt that the chance of a live birth following IVF declines markedly with age. For example, data collected by the HFEA between 1992 and 2004 show that pregnancy rates in IVF begin their gradual but steady decline at around the age of 33 years. In the USA age-related pregnancy rates in IVF begin to fall below 40% once a woman reaches 34 years. By the age of 40, pregnancy rates have declined to 15-20%.
Ovarian reserve – a marker of IVF success
While age provides the greatest statistical prediction of success or failure in IVF, it does not give any true and precise indication in each individual patient. This depends more on the individual quality and quantity of the eggs stored within the ovary and how they will develop and become ready for fertilisation. Ability of the ovaries to generate viable eggs from the earliest follicles in the ovaries is called ovarian reserve. This is one of the most predictive markers of success in IVF.
While overall measures of ovarian reserve also decline with time and age, the rate of this decline varies considerably from one woman to another. For instance, two women at the age of 35 may have quite different measures of ovarian reserve, even though their chronological age is the same. That's why a precise measurement of ovarian reserve is an important step in our ability to predict IVF outcome, especially in women over the age of 35, when their chances of success begin to decline.
Counting on your follicles
A measurement of the total number of the earliest 'primordial' follicles within the ovary is simply not possible, but counting the later developing 'antral' follicles in the ovary provide a reliable alternative. Unlike primordial follicles in the ovary, antral follicles can be seen and counted at the time of the ultrasound scanning.
A high number of antral follicles would suggest an adequate ovarian reserve - and thus a good chance of pregnancy in IVF. Now, however, antral follicle count may be superseded by a more sensitive and predictive measure of ovarian reserve – an Anti Mullerian Hormone test.
In 2008 a review of several studies showed that the measurement of a single hormone - Anti Mullerian Hormone - was just as reliable as antral follicle count in predicting a poor response to IVF.
Anti Mullerian Hormone, or AMH, which can be measured from a blood test, is produced by cells from the outer layer of the follicle. The highest concentrations of AMH are found in the cells of preantral and small antral follicles - and are thus thought to correlate with the number of antral follicles within the ovary.
In recent years AMH has emerged as a predictor of ovarian response to drug stimulation in IVF.A study from Scotland has proposed that women with very low AMH concentration are at risk of either cycle cancellation or poor response to ovarian stimulation. While, those with medium levels have a good chance of a normal response, and those with very high levels may be at risk of ovarian hyperstimulation.
AMH and premature ovarian failure
Measurement of AMH has also been used to help confirm a diagnosis of premature ovarian failure, a distressing condition which can affect young women even in their twenties. While in many cases the exact cause remains unknown, a premature ovarian failure causes infertility as in affected women ovarian reserve had depleted much earlier than would normally be expected. As a result, ovulation and natural conception are no longer possible, and pregnancy can only be achieved by egg donation.
The the accuracy of AMH in predicting the outcome of IVF and ICSI treatment has been confined to studies assessing response to ovarian stimulation - whether a poor, normal or excessive response. Correlation of AMH levels with chances of natural conception are less conclusive. Occasional studies suggest that measures of AMH can help determine the most appropriate treatment approach for each individual patient.
Other factors to pregnancy success
AMH, like antral follicle count only represents the number of follicles present in the ovaries.The chance of pregnancy after IVF depends on much more than just follicle number - embryo quality, quality of the uterine lining, the transfer technique, whether the embryo implants within the uterus and other.
The LWC offers a Fertility MOT package which includes an AMH blood test and pelvic ultrasound scan to assess ovarian reserve. If you would like to find our more or book an appointment, please call 020 7563 4309 or contact us.