Flu vaccine in pregnancy

Flu Vaccine in Pregnancy

Influenza (flu) is a very common and highly infectious disease caused by a virus. It is much more severe than the common cold and results in at least 2-3 days in bed. Catching flu in pregnancy can lead to increased risks for both pregnant women and their babies. Flu complications lead to tens of thousands of hospital stays and an average of 600 deaths in the UK every year. 

This page provides information about:

  • Key facts about the flu vaccine for pregnant women
  • Who is eligible and how to get the vaccine?
  • How effective is the NHS flu vaccination in pregnancy programme?
  • Safety and side effects
  • Ingredients

Key facts about the flu vaccine for pregnant women

The flu vaccine is available between September and January or February every year, and it is recommended that pregnant women get it as early as possible during the season. 

There is strong evidence that pregnant women have a much higher risk of serious illness as a result of flu, compared with the general population. The risks are highest in the last three months of pregnancy. 

Vaccination against flu reduces the risk of complications caused by the virus for women and babies. Serious complications of flu include bronchitis, pneumonia, septic shock (a severe and life-threatening infection of the whole body), meningitis and encephalitis (inflammation of the brain). 

There is also strong evidence that catching flu in pregnancy has an effect on the unborn baby. Babies born to women who have had flu are up to four times more likely to be born prematurely and to have a low birth weight. This may be because flu infection produces an inflammatory response in the body which can trigger premature labour. Flu in pregnancy can even lead to stillbirth or death in the first week of life.

Who is eligible and how to get the vaccine?

The flu vaccine is available to all pregnant women in the UK for free on the NHS, along with other groups at high risk of flu complications. The vaccine can be given at any stage of pregnancy. Women should ask their midwife about where to get the vaccine. In some areas it is available from antenatal clinics and in other areas women receive the vaccine at GP surgeries.

The flu vaccine can safely be given to pregnant women at the same time as the pertussis vaccine. In the 2018-19 flu season, 45% of pregnant women in England (over 300,000 women) received the flu vaccine.

See pages on Influenza (Flu) and the Flu vaccine for more general information.

How effective is the flu vaccination in pregnancy programme?

The flu vaccine works better in some years than others (see the inactivated flu vaccine page for full information about how the vaccine works).

US studies of the H1N1 (‘Swine Flu’) pandemic in 2009 found that pregnant women were four times as likely to develop serious illness and up to five times as likely to be admitted to hospital, compared with the general population. As a result of the evidence from this pandemic, pregnant women were added to the list of groups considered to be at higher risk from seasonal flu.

In the UK between 2009 and 2012, flu was the cause of death for 36 women who died during pregnancy or shortly afterwards. It is estimated that half of these deaths could have been prevented by flu vaccination. See the 2014 summary report from MBRRACE-UK (Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries across the UK). 

Recent research covering almost 20,000 pregnant women over six years in the United States, Australia, Israel, and Canada, showed that the flu vaccine provided a 40% reduction in hospitalisations from flu. The PREVENT (Pregnancy Influenza Vaccine Effectiveness Network) study looked at data between 2010 and 2016 to identify flu-related hospital admissions (see PREVENT research paper).

Studies have shown that women who have been vaccinated against flu are less likely to give birth prematurely, and less likely to have a low-birthweight baby (see the results of a Canadian study). Other studies have shown that women who have the flu vaccine while pregnant are less likely to experience stillbirth (see the results of an Australian study).

Flu vaccination in pregnancy also means that flu antibodies are transferred through the placenta to the baby. This gives the baby some protection against flu for the first few months of life.

The inactivated flu vaccine does not contain any live flu viruses and cannot give you flu.

Safety and Side effects

Seasonal flu vaccination has been recommended in pregnancy for several years in many countries. An increasing number of studies have shown it to be safe in all stages of pregnancy, including the first three months, and to have an important reduction in serious complications for the mother and baby. Read the abstracts of a US study from 2009 and a US study from 2012

Another US study published in 2017 studied the effects of flu vaccination in the first three months of pregnancy. It looked at birth defects in over 52,000 babies who had been exposed to the flu vaccine in the first three months of pregnancy. By comparing this group with over 370,000 babies who had not been exposed to the flu vaccine, the study showed that having the flu vaccine in early pregnancy was not associated with an increased risk of birth defects.

The most commonly reported side effects of flu vaccines are: 

  • pain, swelling, bruising, hardness or redness at the injection site
  • slightly raised temperature (fever)
  • headache
  • sweating
  • aching joints or muscles
  • shivering
  • tiredness
  • feeling generally unwell

Side effects usually last 1-2 days. None of the inactivated flu vaccines contain any live viruses and they cannot give you flu.

There are several different makes of flu vaccine available each year. For more information on side effects, ask for the Patient Information Leaflet for the vaccine you are offered.

Ingredients

Several different brands of flu vaccine are used in the UK each flu season. For full information on ingredients, ask for the Patient Information Leaflet for the vaccine you are offered, or look the brand name up on the electronic Medicines Compendium (eMC).

Inactivated flu vaccines usually contain very small amounts of egg proteins (ovalbumin), as the virus is often grown on hens’ eggs. People who are allergic to eggs should ask their doctor for advice. With specialist medical advice, they may be able to receive a vaccine with a very low ovalbumin content. See more information on egg proteins in vaccines. Public Health England produce an information sheet showing the ovalbumin content of flu vaccines in the current flu season.

Inactivated flu vaccines used in the UK often contain very small amounts of the following ingredients:

Flu vaccines may also contain tiny traces of these products used during the manufacturing process:

  • antibiotics (gentamicin, neomycin, kanamycin or polymyxin), used to stop bacteria growing and contaminating the vaccine
  • formaldehyde, an organic compound used to inactivate (kill) the viruses
Page last updated: 
Monday, September 9, 2019

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