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The truth about TTC and age

8 December 2020

Does your fertility really drop off a cliff on your 35th birthday?

To cut a long story short: it does, but gradually. Since we start learning about the human body, we are told that women’s fertility declines with age. Therefore, is it more difficult to get pregnant after your 35th birthday? Let’s dive into the question of age and fertility for a bit…

We women are born with a fixed number of immature eggs in the ovaries, which is roughly 1-2 million eggs. From that day forward, our number of eggs gradually decreases. In fact, when we get our first period, that number has already dropped to 300,000 or 400,000. Then they continue to fall until we finally reach menopause at the age of 51 on average in the UK. This is the normal decrease in the ovarian reserve than everyone is pretty much aware of.

At every menstrual cycle, an egg will be released during ovulation. The eggs that are not released die and get re-absorbed, in a process called follicular atresia. Some people believe that while they are on contraceptive pills, and therefore preventing ovulation, they keep their eggs. Unfortunately, this is wishful thinking and far from being true. The same applies during pregnancy… eggs are lost during this time too. Atresia is a degenerative process that occurs regardless of whether you are pregnant, have normal menstrual cycles, use birth control or are undergoing fertility treatment.

Some women are born with fewer eggs than average; therefore, they might run out even earlier. This is called Premature Ovarian Insufficiency. Conversely, some women have more eggs than average. This is the case of women with polycystic ovaries who might also have a better ovarian reserve for their age.

However, in general, the fall begins mid-thirties, but especially around your 35th birthday, and unfortunately, there is no way to stop it.  Some lifestyles factors, such as smoking, can also accelerate this natural age-related decline. Smokers appear to experience menopause about 1 year earlier than non-smokers.

Does this fall really affect our fertility?

Yes, it clearly does. It is well known that the best reproductive years are your 20s, as in the 30s- especially after 35 - fertility starts to gradually drop as well as our chances to conceive per month. If a woman in their 30s has around 20% chance of conceiving every month, a 40-year-old woman has a 5% chance. This percentage also applies for assisted conception techniques, including IVF with your own eggs.

It is also important to mention that women do not stay fertile until menopause, most of them are struggling to conceive much earlier, sometimes around early or mid-40s.

Does the quality of the eggs also decrease and impact fertility?

The quality of the eggs also gets poorer as we age. That is why there are more risks of miscarriage or foetal abnormalities in the late 30s or 40s. Unfortunately, there are no tests to measure egg quality, but age gives us an impression.

Having a good or poor-quality egg is all about energy.  An older egg does not have enough energy to divide the cells correctly, a process called meiosis. Therefore some eggs will have too many chromosomes, and others will have too few. If an egg with an abnormal number of chromosomes is fertilised by a sperm, it will create an abnormal embryo. This embryo, in turn, will have too many or too few chromosomes and therefore, on the one hand, it won't be able to implant, or if it does, it might end in a miscarriage or an unhealthy baby.

This egg quality decrease also explains why the chances of getting pregnant after 35 years old are lower, and of miscarriage are higher.  

What should I do if I am trying to conceive and I'm older than 35 years old?

First of all, don’t panic about what you’re reading! Yes, statistically, your chances are lower, but that does not mean it’s impossible. If your MyLotus monitor shows monthly ovulation and you are already timing sex to pregnancy, you are doing things right. However, if pregnancy has not happened in 6 months, you should see a fertility doctor. If your monitor does not show ovulation, do not wait 6 months to ask for professional advice.

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