Flu, also known as influenza, is a viral infection that thrives in cold weather; therefore you will find that most people catch flu more commonly in the winter months and it spreads very easily from one person to another through coughs and sneezes.


What is flu?

The flu virus can mutate (change) very quickly, so each year new strains of flu can be circulating. This is why you need to be vaccinated during each pregnancy, to protect you and your baby from the flu strains that are currently circulating.

Flu is very different to a cold. A lot of people say they have flu when actually they mean they have a cold or another viral infection. Some of the symptoms are similar however, so it can be hard to identify without a blood test.

Flu symptoms typically come on suddenly, unlike a cold which usually gets worse over a few days. With flu, in the morning you could feel normal and by the afternoon you could feel very unwell and unable to carry out your normal day to day activities. People with flu can feel unwell for up to two weeks.

The common symptoms of flu are (you may not experience all of these):

  • High temperature (38c degrees or above)
  • Fever (feeling really hot and really cold)
  • Aching muscles
  • Extreme tiredness
  • Headache
  • Sore throat
  • Dry cough
  • Running or
  • Blocked nose

(Chart showing differences between cold and flu – taken from Centre for Disease Control and Prevention website. https://www.cdc.gov/flu/consumer/symptoms.html

Thinking about those around you; around 60% of people infected with flu do not have any symptoms. That means that you can be at risk of catching flu from others, without even knowing it.

What harm can be caused by catching flu in pregnancy?

Flu itself is not a pleasant infection and can cause you to feel very unwell. Severe flu is more common for pregnant women than non-pregnant women. When you are pregnant the risk of flu causing other problems is higher, especially in the later stages of pregnancy. Flu has the ability to cause:

Worsening of pre-existing health conditions, such as asthma

  • Bronchitis
  • Pneumonia
  • Sepsis (blood poisoning)
  • Hospitalisation
  • Death (rarely)

Your risk of harmful side effects is higher if you also have one or more other known risk factors such as asthma or diabetes.

Your baby is also affected by flu if you are to catch it while you are pregnant and studies show that you are at increased risk of:

  • Miscarriage
  • Poorly grown babies
  • Preterm labour - born before 37 weeks (4 x increased risk)
  • Stillbirth (5 x increased risk)

For patient stories and examples please click here.

What is the flu vaccine?

The flu vaccine is offered for free to high risk groups to try and prevent the spread of infection during the cold months. Pregnant women are included as a high risk group and it is recommended that all pregnant women take up the offer of a flu vaccine.

Flu vaccinations are very safe and cannot give you flu from having the vaccine. The flu vaccine given to pregnant women is inactivated (not live) and is shown to be safe to have at any time in pregnancy.

The flu vaccine is called a quadrivalent vaccine. This means that the vaccine will help to protect you against four strains of flu. Two ‘A strains’ and two ‘B strains’. A new vaccine is produced every year to protect against the strains most likely to be circulating.

When can I receive the flu vaccine?

Pregnant women should aim to have the flu vaccine as soon as possible in pregnancy from the end of September until the end of March. This may be right at the beginning of pregnancy, if you find out you are pregnant in the winter months, or towards the end of your pregnancy if you fell pregnant in the spring/summer months.

Sometimes you may be offered two flu vaccines in your pregnancy, if you have fallen pregnant at the end of one flu season and are still pregnant in September when the next flu season begins. This will cover you for both seasons of flu.

Will my baby benefit from me having the flu vaccine?


If you receive the flu vaccine, you are less likely to catch flu and develop some of the associated complications. If you reduce your chance of catching flu, you also reduce the chance of miscarriage, stillbirth, premature labour and the risk of having a poorly grown baby as a result of flu.

Flu can be really a serious illness in new-born babies and the only way to protect them is to get vaccinated yourself when you are pregnant. Following vaccination, your baby will directly receive some of your newly made antibodies through the placenta which will offer them protection against the same four flu strains for at least the first 8 weeks of their life following birth. Some studies show babies can even be protected from flu for up to 6 months.

There is also another level of protection. By protecting yourself against flu, you are reducing the chance of catching flu and therefore reducing the chance of passing it on to your new-born baby.

Is the flu vaccine safe in pregnancy?

It is not uncommon to worry about the decision to have vaccinations in pregnancy and health professionals understand that you need to have as much information before you make a decision to have a vaccination while pregnant.

Pregnant women have been included in the flu vaccination programme since 2010 following a flu epidemic that caused an increased in the number of deaths. Since its introduction, the flu vaccine has been given to millions of pregnant women across the UK.

Data from over 11 million women who have received the flu vaccine in pregnancy show that, apart from mild pain at the site of the injection, there is no evidence of an increased risk of birth defects or stillbirths.

Although possible, the risk of a severe allergic reaction (also known as anaphylaxis) is extremely low. All medicines and food ingested, injected or applied to the skin have a risk of causing this type of allergic reaction. Anaphylaxis is different from less severe allergic reactions because it causes life-threatening breathing and/or circulation problems. It is always extremely serious but all health care workers providing vaccines know how to treat this should it occur. The risk of a severe allergic reaction following an immunisation is around 1 in 900,000.

There is no risk of catching flu from receiving the flu vaccine. The vaccination provided has been deactivated (killed). Your immune system is likely to be very slightly weaker for 1-2 weeks while your body builds the protection against flu, so you are slightly more susceptible to picking up other bacterial/viral infections in this time should you come in contact with them.

Does the flu vaccine work in pregnancy?

The flu vaccine is the best way of protecting yourself against the virus during pregnancy. Currently the vaccine is thought to be around 60-70% effective for pregnant women and near 90% effective for babies born from vaccinated mothers.

Women vaccinated in pregnancy more than halve the risk of developing flu in pregnancy.

The flu vaccine reduces the risk of women having a premature baby by more than two thirds.

The flu vaccination, if given to pregnant women, has been shown to reduce the chance of babies being admitted to hospital with flu.

What side effects may I experience?

It is important to know that you cannot catch flu from having the flu vaccine. Most people do not even feel any side effects following a vaccine however for those that do you could expect the following:

  • Common – Discomfort, swelling or redness to site of injection
  • Unlikely – Headaches, shivering, mild fever or slight muscle aches
  • Extremely Rare - severe allergic reaction

If the side effects are bothering you, paracetamol should help relieve some of the symptoms.

What else can I do additionally to protect myself?

Encourage your partners and family members to have a flu vaccine – either privately through a pharmacy or through their GP if they are in a high risk group.

If you have young children, click here to see if they are eligible for a free flu vaccine. If your child is offered a flu vaccine at school, it is encouraged that you consider that your child receives the vaccines to protect them and to help stop the spread of infection within your household.

Avoiding contact with family or friends who you suspect might have flu.

Wash your hands thoroughly and regularly with warm water and soap.

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