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Cytomegalovirus: What is CMV?

What is CMV and how do we get it? How do we avoid it?

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What is CMV?

Many people – probably about 60% of us - have been infected with Cytomegalovirus (CMV) without even knowing it. It is a very common virus that may have no symptoms at all or may have symptoms a bit like a common cold. The only way to know if you have had it is by doing a blood test looking for antibodies to CMV - there is no immunisation available.

How do people get CMV?

It is passed from one person to another via body fluids such as saliva, blood, semen, tears, urine, mucus, breast milk or blood transfusion.

Why is it important in pregnancy?

If a pregnant person is infected with CMV, it is not possible to predict whether a baby will become infected or how it may affect them. In the event that an unborn baby is affected, it may have long-term health problems such as deafness, seizures or developmental delay. About 1 in every 200 babies is born with congenital CMV. About 1 in 5 of those will have birth defects or other long-term issues.[1]

[1] CMV Fact Sheet for Pregnant Women and Parents | CDC

How are sperm donors tested for CMV?

They are tested for CMV antibodies in their blood prior to donating sperm and again at least three months after donating sperm. They are tested for two types of antibodies: IgM and IgG. IgM antibodies indicate acute or active infection with CMV and this is when the risk of passing on infection is the highest, so their samples would not be used. IgG antibodies indicate past infection.

There is a theoretical risk that a CMV positive donor could pass CMV infection via their semen samples to a recipient using those samples. Preventing the use of sperm from donors with active infection (CMV IgM positive); washing the samples for IUI and IVF; and freezing the samples further decreases the risk.

Should a CMV negative recipient use a CMV positive donor?

If someone has not been exposed to CMV in the past, (determined by blood testing), and they are concerned, they can choose a CMV negative donor. However, the risk of contracting CMV in pregnancy is greater from exposure to other people around them than it is from the use of sperm from a CMV positive donor.

Avoiding CMV

The best prevention of infection or re-infection of CMV is by avoiding contact with bodily fluids and ensuring that you wash thoroughly after, eg changing nappies. The saliva and urine of small children with CMV have high amounts of the virus.[2] Taking precautions such as washing hands thoroughly after contact with any bodily fluids and avoiding contact with saliva and urine from small children will reduce the risk.

If you have any concerns you can discuss these with the Fertility Associates team.

[2] Ibid.

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The Biological Clock

This tool indicates:

  • Natural conception per month if you have no fertility issues
  • IVF success rate at the same age
  • When to seek help after months of unsuccessful attempts

If you are concerned at any stage – we recommend booking a doctor appointment or a free nurse consultation. The sooner you make a plan the better your chances in the long term.

When to seek advice early

  • If you have polycystic ovaries, endometriosis, or have been through a cancer diagnosis; we recommend you get in touch quickly so we can talk you through all your options and give you the greatest possible chance of success.
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Body Mass Index calculator

Being overweight or underweight can reduce fertility, so it is important to keep your body weight within the normal healthy range.

Body Mass Index (BMI) is an indication of your body weight and can be calculated by dividing weight by height. You should aim for a BMI of between 20 and 25, as this will optimise your chances of conception.

Woman’s BMI below 19

Even in these modern times, nature knows best. If a woman's BMI falls below 19, the body senses famine and ovulation is switched off to prevent the risk of having a baby with malnutrition. Excessive exercise can reduce body fat and increase muscle mass to a point where periods cease for the same reason. Risk of miscarriage is also increased in women with a low BMI.

Being underweight

If a woman's BMI falls below 19, the body senses famine and ovulation is switched off to prevent the risk of having a baby with malnutrition. Excessive exercise can reduce body fat and increase muscle mass to a point where periods cease for the same reason. Risk of miscarriage is also increased in women with a low BMI.

BMI’s greater than 30

This can reduce fertility by 50%. Pregnancy for women with a 30+ BMI is often associated with problems such as maternal diabetes, high blood pressure, big babies and increased risk of caesarean section.

Add your height and weight to calculate your BMI