Sorry chaps, it's expectant mums who are worst hit by flu: Pregnancy makes the immune system go haywire when fighting the virus

Cells from pregnant women showed hyperactive immune response to flu

White blood cells produced more cytokines and chemokines

Cytokines and chemokines help attract other immune cells to infection site

This could clog up the lungs with an influx of immune cells, experts said

Catching flu when pregnant heightens risk of pneumonia and death

Pregnant women urged to have flu jab to protect against this response

Studies planned to test pregnant women's responses to other viruses' 

Mothers-to-be are worst hit by flu than other groups because pregnancy makes the immune system go into overdrive when fighting the virus.

It was previously thought immune responses were weakened by pregnancy to prevent the woman's body from rejecting her foetus.

But a new study is the first to examine the reactions of immune cells taken from pregnant women to influenza viruses, including the H1N1 strain that caused the 2009 flu pandemic.

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Pregnant women are worse hit by flu than other groups because pregnancy triggers a stronger immune response to the virus, say researchers 

Researcher Dr Catherine Blish, assistant professor of infectious diseases at Stanford University in the U.S. said: 'We now understand that severe influenza in pregnancy is a hyperinflammatory disease rather than a state of immunodeficiency.

'This means that treatment of flu in pregnancy might have more to do with modulating the immune response than worrying about viral replication.'

The researchers took immune cells from 21 pregnant and 29 healthy, non-pregnant women and exposed them to different flu viruses in the laboratory.

 

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Cells taken from women six weeks after they had given birth were also tested.

Pregnancy boosted the immune system's response to swine flu by affecting two types of white blood cell, natural killer (NK) and T-cells.

Compared with those from non-pregnant women, both cell types produced larger amounts of cytokines and chemokines, molecules that help attract other immune cells to the site of an infection.

This could lead to lungs becoming clogged up by an influx of immune cells, said Dr Blish.

FLU DURING PREGNANCY 

There is good evidence that pregnant women have a higher chance of developing complications if they get flu, particularly in the later stages of pregnancy. 

One of the most common complications of flu is bronchitis, a chest infection that can become serious and develop into pneumonia.

If you have flu while you're pregnant, it could mean the baby is born prematurely or has a low birthweight, and may even lead to stillbirth or death in the first week of life.

The flu vaccine is normally available from September until around January or February each year in the UK and is free for pregnant women.

Source: NHS Choices 

Catching flu when pregnant, especially pandemic strains, is known to heighten the risk of pneumonia and death.

Both strains of flu also caused NK and T cells to be activated in a greater variety of ways in pregnant than nonpregnant women, the study found.

Researchers said the findings could lead to new treatment for pregnant mothers with flu.

Further studies are planned to test whether pregnant women's immune response would be similarly hyperactive with other viruses.

Professor Blish said she suspected 'this is peculiar to influenza' as having the virus during pregnancy quadruples a woman's risk for delivering her baby prematurely.

She said: 'I wonder if this is an inflammatory pathway that is normally activated later in pregnancy to prepare the body for birth, but that flu happens to overlap with the pathway and aberrantly activates it too early.'

She urged all women hoping to conceive or who are pregnant to ensure they had a flu jab 'to avoid this inflammatory response.'

The flu vaccine is normally available from September until around January or February each year in the UK and is free for pregnant women.

The study was published in the journal Proceedings of the National Academy of Sciences.

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Pregnant women are being urged to have the flu jab to avoid the inflammatory response to the flu virus

Read more: http://www.dailymail.co.uk/health/article-2765393/Sorry-chaps-s-expectant-mums-worst-hit-flu-Pregnancy-makes-immune-haywire-fighting-virus.html#ixzz3E5R9HZPh 
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