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What can AMH tell you about your fertility?

The hormone AMH is produced within your ovaries, but what can it tell you?

Wouldn't it be great if there were a crystal ball that could tell us how much time we have left to start a family and how easy we'll find it to get pregnant? Sadly, even with modern science, there is still no crystal ball. This is because many factors influence your chances of conceiving, from the quality of your eggs, whether (or not) you're ovulating, whether there might be something stopping your partner's sperm from reaching your eggs – even the quality and quantity of his sperm. Another factor that influences your fertility is the number of eggs you have - this is called your ovarian reserve. All women are born with all the eggs they will ever have. They have between 1 and 2 million eggs when they are born, and even before they start having periods, they lose thousands of eggs a year. By the time a girl reaches puberty, she will have around 300,000 – 400,000 eggs remaining in her ovaries, and these will continue to decline until menopause, when she has no viable eggs left. So how can you tell how many eggs you have left in your ovaries? And if you knew the answer to that question, what could it tell you about when you should think about having children? One way to get an idea of whether the number of eggs in your ovaries is normal for your age is to have an Anti-Mullerian Hormone (AMH) Blood Test. AMH is a hormone produced by the follicles (tiny egg-containing sacs) growing in your ovaries. When you ovulate, your ovary releases one of these eggs into the fallopian tube for fertilisation. AMH correlates strongly with the number of follicles (and therefore eggs) you have – and as we know, these follicles decline with age. If a test shows that you have a lower AMH level than the average for your age, this could mean that you have fewer eggs left and could reach menopause earlier than average.

What can AMH tell me about when to start a family?

First, it is important to say that a lower-than-average AMH level for your age won't tell you much about your chances of getting pregnant. You only need one healthy egg to meet one healthy sperm for conception to occur. And even if your AMH level is lower than other women your age, that doesn't mean that you won't still produce one healthy egg. The key is whether the egg is genetically normal, which is influenced much more by your age than your ovarian reserve. What an AMH Blood Test might tell you is whether you may reach menopause earlier than average. The average woman reaches menopause (defined as having had no periods for a year) at age 51. However, in the ten years preceding menopause, the quality and quantity of eggs she produces declines rapidly. If an AMH test suggests you might reach menopause earlier than average – then you might decide to bring your timeline for having children earlier. If you aren't in a long-term relationship or are not ready to start a family, you may choose to freeze some of your eggs. If you are starting fertility treatment or have decided to freeze some of your eggs, an AMH Blood Test can help your fertility doctor estimate how many eggs might be retrieved in a cycle. Your fertility doctor may use drugs to stimulate your ovaries to produce more eggs than in a normal cycle. These are then harvested to be frozen or fertilised in vitro. Women starting fertility treatment with low AMH may not respond well to the drugs given to stimulate egg production, meaning fewer eggs are harvested. This could mean that her chances of successful IVF are lower and that she may need to undergo more cycles to achieve a pregnancy. AMH tests for fertility treatment need careful interpretation by your fertility doctor, who will also consider other factors, like your age.

So, what does a normal or high AMH level tell me?

Sadly, we can't conclude that just because your AMH is normal or higher than other women your age, that you have all the time in the world to start a family. This is because an AMH test doesn't tell us anything about your eggs' quality – only the quantity of developing follicles in the ovaries. As women age, the DNA (genetic material) in their eggs degrades, which reduces the chance of a viable pregnancy. This happens from your 20s onwards and is irrespective of your AMH level. The incidence of having abnormal eggs increases more rapidly from age 35; women in their 20s have mostly normal eggs while women in their 40s will have mostly abnormal eggs, making it harder for conception or a successful pregnancy to occur. So, while a normal (or high) AMH test can give you some reassurance that you don't need to rush things, your "biological clock" is still ticking. Sometimes AMH is high because of a condition called polycystic ovarian syndrome (PCOS). This is a common condition where your ovaries produce high numbers of follicles every month. These follicles can take a long time to develop into a viable egg leading to irregular periods, making it more difficult to predict ovulation and get pregnant. As AMH correlates with follicle numbers, women with polycystic ovaries often have higher than normal AMH levels. If your AMH level is higher than expected, it would be worth following up with a Polycystic Ovary Syndrome Blood Test to check whether polycystic ovaries could be the reason. You can read more about polycystic ovaries and fertility here. An AMH test isn't quite the crystal ball we'd like it to be. It can't predict whether you have healthy eggs, and it can't identify whether a physical problem might affect you or your partner. What it can do is help you understand your fertility timeline. If an AMH test is normal for your age, it may mean that you don't need to rush. If an AMH test is higher than expected, you may want to investigate PCOS. And if an AMH test shows that your levels are lower than average for your age, then you might want to bring your timeline for having children forward. Just knowing helps you to make informed choices.