Assisted conceptionTrying to conceive

Exactly how common is infertility?

Although we know a lot of people suffer from infertility, it has been difficult for experts to agree on exactly how many people are unable to naturally conceive.

Infertility is sometimes defined in different ways and measured using different assumptions, so scientists are often measuring slightly different values when trying to find out how many people are infertile. This has made it difficult for experts to agree on a concrete figure when it comes to how common infertility is, and comparisons of infertility levels over different timescales and countries are nigh on impossible.

How many people don’t have trouble conceiving?

What researchers are pretty sure about is that, when a woman is under 40, about 80 – 85% of couples will conceive within a year if they aren’t using contraception and are having sex every two to three days. Research has also shown that in about half of the couples that do not conceive after one year of un-protected sex, pregnancy will be achieved in the second year of trying.

So the amount of couples who are infertile must fall within a zero to 20% range, and the number is likely to be under 20%, since so many couples fall pregnant within the second year of trying.

One study from 1985 claimed that one in six couples (about 17%) in the UK seek medical help to conceive. But other experts believe that this is an underestimate, as it’s hard to account for all the couples with fertility problems who do not come forward to see a doctor, couples who stop trying to conceive or couples who have previously been infertile but have been treated. What’s more, our busy, modern, lifestyles are pretty different to those that people led in 1985, so this could have a big influence on infertility levels.

Using the classic definition of infertility (when a sexually active couple fail to achieve pregnancy after one year of un-protected sex), one important and more modern study has helped to shed light on how common infertility really is. To measure infertility levels in the USA, the researchers used ‘the current duration approach’ – a method which is based upon the length of time couples have been trying to conceive and which is known for being very accurate. They found that infertility levels were 15.5% in the USA – a figure that is pretty similar to the number the British study in 1985 ended up with.

How can we tell which figure is right?

But – as is often the case with scientific disputes – other researchers disagreed. One study found that only 6% of married US women aged 15 – 44 (and therefore their partners) were infertile.

Really, there are tons of studies that have tried to work out how common infertility is, and a lot of them have reached different answers. It can all get a bit confusing when even the experts are reaching different answers and disagreeing. But, by looking at the average figure that the majority of infertility studies are reaching (at least those that have been carried out well) – we can hope to get an accurate estimate for how common infertility is.

If we take a look at three well-renowned studies carried out across different time scales (1968, 1996 and 2012), we can see that they all reached figures for infertility in the US ranging from 12 – 18%. Indeed, looking at the whole selection of studies measuring how common infertility is, shows us that values for infertility prevalence of around 15% come up again and again, and so, this is the figure that most scientists now accept to be correct.

Infertility levels are different in across different regions

In an interesting twist, infertility seems to vary in its levels across the world, meaning the 15% mark holds true for western countries, but not for countries in the developing world. Poorer countries – especially those in Africa – tend to have a much higher incidence of infertility. This is because there is often low knowledge, use of and access to health services – meaning people are more likely to contract conditions that damage their fertility, such as sexually transmitted diseases (STDs). People in poorer countries also experience higher levels of secondary infertility – where infertility develops after a person has previously had children – due to poor hygiene after childbirth, miscarriages and abortions.

You might be wondering why it’s so important that we know how common infertility is. Is it not enough to just know that a handful of people will be affected by the condition and to just leave it at that? But the fact of the matter is, the more we know about infertility (including the more we know about how often it occurs), the easier it will be for healthcare professionals and society as a whole to manage and cope with the hefty burden it brings.

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